. » ¥ ) x ’ ‘an &! \ > ait a3 BAP TP R578 QEs eters Sey Se pe ee a 7, Pi ‘ ae re ie , Leys * oe v. J dl’ he ” * ea ate ar f sn hel ait edie Bai ada ee tee a Ce iis ae ee * he ‘ - a i ote BO pe a ae oe i aaNet VI ETERS eee te ee oe 4 tt 7 (vee AP ae y ST Notes . th Pe oh X =F PR we Caan In CE Pa ——— eee: = id ¥ W “4 4 ’ | JOURNAL OF THE ROYAL MICROSCOPICAL SOCIETY: CONTAINING ITS TRANSACTIONS AND PROCEEDINGS, AND A SUMMARY OF CURRENT RESEARCHES RELATING TO ZOooLwtLoGy AND BOTAN YT (principally Invertebrata and Cryptegamia), MICROSCOPYW, Sz. Edited by FRANK CRISP, LL.B. B.A, One of the Secretaries of the Society and a Vice-President and Treasurer of the Linnean Society of London ; WITH THE ASSISTANCE OF THE PUBLICATION COMMITTEE AND A. W. BENNETT, M.A., B.Sc., ¥F. JEFFREY BELL, M.A., Lecturer on Botany at St. Thomas's Hospital, Professor of Comparative Anatoury in Ki ing’s College S. O. RIDLEY, M.A., of the British Museum, JOHN MAYALL, Jon., anD FRANK H. BEDDARD, M.A., FELLOWS OF THE SOCIETY. Ser ll V OE IV PARA: PUBLISHED FOR THE SOCIETY BY - WILLIAMS & NORGATE, LONDON AND EDINBURGH. 1884. GD =P) 0 JAN 20 1 Royal Microscopical Society, (Founded in 1839. Incorporated by Royal Charter in 1866.) The Society was established for the communication and discussion of observations and discoveries (1) tending to improvements in the con- struction and mode of application of the Microscope, or (2) relating to Biological or other subjects of Microscopical Research. It consists of Ordinary, Honorary, and Ex-officio Fellows. Ordinary Fellows are elected on a Certificate of Recommendation signed by three Fellows, stating the names, residence, description, &c., of the Candidate, of whom one of the proposers must have personal knowledge. The Certificate is read at a Monthly Meeting, and the Candidate balloted for at the succeeding Meeting. The Annual Subscription is £2 2s., payable in advance on election, and subsequently on Ist January annually, with an Entrance Fee of £2 2s. Future payments of the former may be compounded for at any time for £31 10s. Fellows elected at a meeting subsequent to that in February are only called upon for a proportionate part of the first year’s subscription, and Fellows absent from the United Kingdom for a year, or perma- ney residing abroad, are exempt from one-half the subscription during absence. Honorary Fellows (limited to 50), consisting of persons eminent in Microscopical or Biological Science, are elected on the recommendation of three Fellows and the approval of the Council. Ex-officio Fellows (limited to 100) consist of the Presidents for the time being of such Societies at home and abroad as the Council may recommend and a Monthly Meeting approve. They are entitled to receive the Society’s Publications, and to exercise all other privileges of Fellows, except voting, but are not required to pay any Entrance Fee or Annual Subscription. The Council, in whom the management of the affairs of the Society is vested, is elected annually, and is composed of the President, four Vice- Presidents, Treasurer, two Secretaries, and twelve other Fellows. The Meetings are held on the second Wednesday in each month, from October to June, in the Society’s Library at King’s College, Strand, W.C. (commencing at 8 p.m.). Visitors are admitted by the introduction of Fellows. In each Session two additional evenings are devoted to the exhibition of Instruments, Apparatus, and Objects of novelty or interest relating to the Microscope or the subjects of Microscopical Research. The Journal, containing the Transactions and Proceedings of the Society, with a Summary of Current Researches relating to Zoology and Botany (principally Invertebrata and Cryptogamia), Microscopy, &c., is published bi-monthly, and is forwarded gratis to all Ordinary and Ex- officio Fellows residing in countries within the Postal Union. The Library, with the Instruments, Apparatus, and Cabinet of Objects, is open for the use of Fellows daily (except Saturdays) from 10 a.m. to 5 p.m., and on Wednesdays from 7 to 10 p.m. also. It is closed during August. Forms of proposal for Fellowship, and any further information, may be obtained by application to the Secretaries, or Assistant-Secretary, at the Library of the Society, King’s College, Strand, W.C. a 2 p atron. HIS ROYAL HIGHNESS ALBERT EDWARD, PRINCE OF WALES, K.G., G.C.B., F.BS., &e. RD PARED AAD IDI DIDI III IDI Past-Presioents. Elected. Ricuarp Owen, C.B., M.D., D.C.L., LU.D., F.R.S....... 1840-1 Jonas) binge, ID). WSs Goon 6c od0osobo0dDdGDDOONS 1842-3 ‘Wrong [Bian Wish og occ oo Gago Ao OUD Do UgDOCa00000 1844-5 James Scort BowerBank, LL.D., F.B.S...........006- 1846-7 Giamncin Joie Iliteh oo gobo acaoodoadag Dodo ddDOOoe Dd 1848-9 /Aipimnons Lina, WiGID SS Teese Shes adecdc5oa050oGdnda0 1850-1 (Ginoein GiNorONt, WE OUS6 GooguooboogGonondooeosdac 1852-38 Wituiam Bensamin Carpenter, C.B.,M.D.,LL.D.,F.R.S. 1854-5 GORGE SHADBOLD sche tio Seidusiai sw ote tones wie eis eats eels euetels 1856-7 Epwin Langester, M.D., LL.D., F.R.S................ 1858-9 Gui SMstonens) Qheistenin wa Jesbao gosqu0ccab0gac0d0n0K 1860 Ropert JAMES Farrants, F.R.C.S............ a bec eed ea 1861-2 GHARGES DROOKE; (MEAL. SH RS. cc cies e oles were aires 1863-4 Jisunnry (Cnnisriiay Wo vSBs 566 ScoGsG 0505550 000000K0 1865-6-7-8 Rev. JosupH Banonort Reapz, M.A., F.R.S........... 1869-70 Vili TAM OTOHEN HARKER iHohy.So\rietelsencisies cies ceelereneie 1871-2 @HARUNS He DROOKE, HVAC HOR Sng. «cto eee co oar etes 1873-4 Henry Currton Sorsy, LU.D., F.R.S................ 1875-6-7 Henry James Suack, F.G.8....... aye. wile SW 2ANe alate re eae ee 1878 LioneL 8. Beane, M.B., F.R.C.P., F.R.S.............. 1879-80 Pe AR TIN eUINCAN.@OVL, Ek hveSo less tierelelc «nee 1881-2-3 COUNCIL: Euectep 13TH Fesruary, 1884. Areswent. Rev. W. H. Datuineer, F.R.S. Vice-Presidents, Joun AntHony, Esq., M.D., F.R.C.P.L. Pror. P. Martin Duncan, M.B., F.BS. James GuatsHer, Esq., F.R.S., F.R.A.S. *CHaRLES StEwart, Esq., M.R.C.S., F.L.S. Creusurer, Lionen §. Bratz, Hsq., M.B., F.R.C.P., F.R.S. Secretaries, *Frank Crisp, Esq., LL.B., B.A., V.P. & Treas. LS. Proressor F. Jerrrey Bewu, M.A., F.Z.S. Ciwelve other Tlembers of Council. ALFRED WILLIAM Bennett, Esq., M.A., B.Sc., F.L.S. *“Rospert Braituwaite, Esq., M.D., M.R.C.S., F.L.S. G. F. Dowprswett, Esq., M.A. J. Wixi1am Groves, Esq. Joun H. Ineren, Esq. Joun Martuews, Esq., M.D. Joun Mayatt, Esq., Jun. Apert D. Micnart, Esq., F.LS. *Joun Miniar, Esq., L.R.C.P.Edin., F.L.S. Witiram Mitztar Orp, Esq., M.D., F.R.C.P. Urpan Pritonarp, Esq., M.D. Witu1am Tuomas Surroix, Esq. Hrbrarian and Assistant Secretarp. Mr. James West. * Members of the Publication Committee. i wy ¥ 4, { hy, ee CONTENTS. TRANSACTIONS OF THE SocIETY— I.—The Constituents of Sewage in the Mud of the Thames. By Lionel 8. Beale, F.R.S., Treas. R.M.S. (PlatesI.-IV.) Partl 1 II.—On the Mode of Vision with Objectives of Wide Aperture. By Prof. E. Abbe, Hon. F.R.M.S. (Figs.1-7) .. .. 4, 20 III,—Observations on the Life-History of Stephanoceros Hich- horn. By T. B. Rosseter, F.R.M.S. (Plate V. Figs. 1-3.) Part 2 169 IV.—The President’s Address. By Prof. P. Martin Rae Tg tasty \WWoltGLESI es 54 0 a6) on co ep 173 V.—On the Mineral Cyprusite. By Julien Deby,C.E.,F.R.MS. _,, 186 VI—List of Desmidies found in gatherings made in the neighbourhood of Lake Windermere during 1883. By J. P. Bisset. (Plate VY. Higs.4-7).. .. .. «o «. 45 192 VII.—On the Formation and Growth of Cells in the Genus Polysiphonia. By George Massee, F.R.M.S. (Plate VI.) ,, 198 VIII.—On the Estimation of Aperture in the Microscope. By the late Charles Hockin, jun. (Plate VIL) .. .. .. Part3 337 IX.—Note on the Proper Definition of the Amplifying Power of a Lens or ert ahs Prof, E. aay Hon. F.R.M.S. PAGE (ities 43) 00 90 5a ae G0, (00 00'. 00 Go. 00. 348 X.—On Certain Filaments observed in Surirella bifrons. By John Badcock, F.R.M.S. (Figs.49 and 50) .. .. i 352 XI.—Researches on the Structure of the Cell-walls of Diatoms. By Dr. J. H. L. Flogel. (Plates VIII. and IX.) .. .. Part 4 505 XII.—On a New Microtome. By C. Hilton eee te td igs 83 and 84) Sry cath Geis 00 3 523 XIII.—On some Appearances in the Blood of veep hes with Reference to the Occurrence of Bacteria therein. By G. F. Dowdeswell, M.A., F.R.M.S., &. «2 «2 26 «2 525 XIV.—On Protospongia pedicellata, a new compound Infusorian. By Frederick Oxley, F.R.M.S. (Figs. 85 and 86).. .. 5, 530 XV.—On a New Form of ee Prism. mh C. D. Ahrens. (Higss SiiandiSS) ies. aes <-- sce XVI.—Researches on the Structure of the Cell-walls ¢ of Diatoms (continued). By Dr. J. H. L. ore ee IX., X. and XI. and fig. 119) .. .. .. .. o Part 5 665 XVIL—On Drawing Prisms. By J. reagents M.D. Cantab., F.R.C.P., F.R.M.S. (Figs. 120-2) .. .. .. tA 5s 697 Vill CONTENTS. PAGE XVIIL.—Description and Life-history of a new Fungus, Milowia nivea. By G. Massee, F.R.M.S. (Plate XID.) .. .. «. . Part 6 844 XIX.—Notes on the Structural Characters of the Spines of Echinoidea. (Cidaride.) ae Prof. F. Jeffrey Bell, M.A., rSTeXce 70). = i @/ ed [2h vey Ul ES) Yer ODIO 5s 846 XX.— Researches on the Structure of the Cell-walls of ee Eupodiscus. By Dr. J. H. L. Flogel. (Fig: 144) .. .. ,, 851 - XXI.—On some Photographs of Broken Diatom Valves, taken by Lamplight. By Jacob D. Cox, LL.D., F.R.MS. .. .. 853 SuMMARY OF CURRENT RESEARCHES RELATING TO ZOOLOGY AND BoTANY (PRINCI- PALLY INVERTEBRATA AND CRyYpPTOGAMIA), Microscopy, &c., INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERs.* 27, 201, 354, 535, 704, 859 ZOOLOGY. A.-—GENERAL, including Embryology and Histology of the WORE, Influence of Gravity on Cell-division .. .. so pa Leta I OT Influence of Physico-Chemical Agencies upon the Devon ment of the Tadpoles of Rana esculenta . : ee 29 Colours of Feathers .. . (tia icici ll Gone MpoMatzcsth ios 29 Rudimentary Sight apart rer om Eyes Gp.) te onl don Sony mics 31 Commensalism between a Fishanda Medusa .. . % 35 Development of the Optic and paca y Organs of iFosmen Embryos 00 co oo oo deta PADI Eggs of Birds .. rs 203 Chemical Composition ys the Hog apa its Brvcopes im the Common Frog .. + Sy pegeleyp Mesee te aeis mss 203 Zoonerythrine and other As) PyTeao a Sees ati: Sea ence 204 Commensalism between a Fish anda Meduse .. .. 5 204 Contributions to the History of the Constitution of the OWL. 00 00 08 30 00 0a oo oo oo Lents} Bast Origin of Detar 4c Siamentatie 00 00g 355 Gastrea Theory .. .. 00 357 Changes of the Generative Daadhnais before Geese. Ae ote eh 357 Development of Spermatozoa eae weyers ee immer, 359 Human Embryo .. . aM Abate Cee ase a 359 Placentoid Organ in ihe Binbr yo of Bir oe A ica: Cicaew 360 Development of the Spinal Nerves oe Tritons so Rey aes 360 FRUIT Off JHAGRUOWEMS co 0p 00 0000 assis 360 Development of Lacer in ag gilis ae 861 Development of Teleostei ” : Shas Got gh 362 Influence of High Pressures on assay Baepinsine Re eaae gs 362 On some Appearances in the Blood of Vertebrated Animals with reference to the Occurrence of Bacteria therein .. Part 4 525 * Tn order to make the classification complete, (1) the papers printed in the oo « « bart 4 048 Histology of the Digestive Ghai of H Ap seg easy 549 Aplysie of the Gulf of Naples .. .. «2 «2 oF oF 9 550 Morphology of the Acephalous Mollusca .. .. «. . Bs New Type of Mollusc .. .. 00 60 00 050 LEHR) 727/ Taking-in of Water in Relation to the Vesories System of Molluscs .. .. e Eyes and other Shranaasens m the Shells # Chitonidee Renal Organs of Embryos of Helic .. .. .. «2 «8 45 729 Nervous System of Parmophorus australis .. 3 Organization of Haliotis .. ee eee os oe 730 Absorption of the Shell in Aur ceueeen do oo oo co oa gf 730 Development of the Digestive Tube of Limacina.. : © Operculum and Foot-glands of Gastropoda... .. .. « Part 6 869 CONTENTS. Latent Period in the Muscles of Helix a5 100 Affinities of Onchidia .. 416 Dimorphism of the Spermatozoa in Paladin Mode of Action of Shell- and Rock-boring Molluscs . Action of Sea Water on Molluscs Molluscoida. Egg and Egg-membranes of Tunicata .. Simple Ascidians of the Bay of Naples Urnatella gracilis, a Fresh-water Polyzoan Structure and Development of pgs Development of Salpa .. c 60 Budding of Anchinia .. .. 00 30 Morphology of Flustra ep neIpn- ‘eupaniie 00 Anatomy of Rhopalea .. Simple and Compound Desirtry § Digestion in Salpa See CW) clo Oe Fresh-water Bryozoa Supposed New Species of Cr intelia Segmentation of Ascidians Relation of the Nervous System of the Adult Usain % that of the Tailed Larve .. Segmentation of Simple Ascidians Development of Social Ascidians .. Tunicata of the ‘ Triton’ Organization of Anchinia .. .. . Closure of the Cyclostomatous Bryozoa Arthropoda. Aspects of the Body in Vertebrates and Arthropods .. a. Insecta, Respiratory Centre of Insects Chordotonal Sense-organs and the Hearing of econ Number of Segments in the Head of Winged Insects... Protective Device employed by a See igs ea Formation of Honeycomb .. .. BD Mouth-organs of Rhynchota Development of Genital Organs of reat Genital Ducts of Insects .. .. -. « Thoracic Musculature of Insects.. Early Developmental Stages of Viviparous ‘Aphides oC Chlorophyll in Aphides Genealogy of Insects Development of Antenne in ipscats Experiments with the Antenne of Insects .. Epidermal Glands of Caterpillars and Malachius Classification of Orthoptera and Neuroptera Sucking Organs of Flies . 30 48 Visceral Nervous System of Per pelarata antantclls . Part 6 Pat 6 .. Part 6 . Part 1 oo ” On ” iG Pare 2 xl PAGE 870 870 871 872 873 213 214 214 215 368 369 371 552 731 732 732 733 873 874 875 _ 875 878 878 879 866 217 218 218 219 220 220 223 xii CONTENTS. a PAGE Pulsating Organs in the ce of Hemiptera 3, :. «. Part 224 Corabus bifasciatus® “a. 25 ae feet en Ses) oe ae PAILS OIA Mouth-parts of Diptera «1 ss oe ou we ewe 372 Mouth-organs of Lepidoptera RUE nl Pehueter ose he ang 372 Malpighian Vessels of Lepidoptera .. 1. +s 1s 08 15 373 Abdominal Muscles of the Bee .. .. «» «6 «+ « 1459 373 TAO OP IMSCOD ea co od 9 OG) ba Foe Bo 8 tO, 374 Aphides of the Hlm — .. Be a rpte aae lee 374 Attraction of Insects by Phallus faa Capris: BG) 100) Oe = oh 420 ULGTOUGULCLLCT Meare ate) ele .. Part 4 552 Development of Gcanthus niveus and is paras Teleas sO 553 Origin of Bees’ Cells .. «. n0 06 oO. 00 80° 504 Closed Poison-glands of Cater lens Som uot one! dd. toa op 555 Gills of Insect Larve .. .. iva Gbe OG 5 555 Dangers from the Eacrement of Whee... 30 00 50 50g 506 New Type of Elastic Tissue, observed in the Larva of Eristalis .» « Part 5 733 Submaaxillary of the i of Mandibulate Tec reas te as 733 Structure and Function of Legs of Insects.. .. 00. oD 734 Organs of Attachment on the Tarsal Joints of Trans Spee es 736 Locomotion of Insects on Smooth Surfaces .. .. .» «8 45) 716 & 737 Organs of Flight in the Hymenoptera .. .. 500 0h 738 Poison of Hymenoptera and its Secreting Onnne. On Par Oe wey 739 Development of Cerocoma Schreberi and Stenoria apicalis.. ,, 739 Dipterous Larve .. .. of 90 bo. no. 739 Larve of North American Lepidoptera Fol ac oa DO = ep 740 Drinking Habit of a Moth .. «1 «. oh ars 741 Movements of the Heart of Insects dur eg Wctumonnnanal .. Part 6 879 TRONG® Of ISG 00 c0 00 O02 00 00 of so 880 JGGIR5 Of JPOP MOPS 00° 00 600s op 880 Sting of Mellifera 006 ae » 880 Anatomy and Functions of the Tonge of the. Hone Bee (Worker). aia Meise Aig? Ge Soap icles 55 881 “* Tgnivorous Ant ee 20 no 00 OO 882 Aquatic Lepidopterous Larve 5 882 Maxillary Palp of Lepidoptera .. ae cues 883 Development of Viviparous Aphides 0 883 Systematic Position of Pulicide .. Fa 884 Structure of Proboscis of Blow-fly » 003 8. Myriopoda. Head of Scolopendra co 0 on on LE) YEE Nerve-terminations on Antenne of Gilcanaina . «» Part 4 556 Ovum of Geophili 00°06 56 oc 5 057 y. Arachnida. Testis of Limulus... .. .. Ad. 80 . Parti 49 Polymorphism of Sarcoptide «53 49 Vitelline Nucleus of Araneina : .. Part 2 224 Restoration of Limbs in Tarantula .. x 225 CONTENTS. Morphology of Plumicolous Sarcoptide .. Skeletotrophic Tissues and Coxal Glands of Limulus, Scorpio, and Mygale.. .. .. « Type Series of British Oribatide Poison-apparatus and Poison of Scorpions .. Structure and Function of the Liver a Spiders .. Anatomy of Acarina oth doo 60 Michael’s British Or eB. 00 aC Development of Spiders... .. .. «» « Anatomy of Spiders .. 1. 25 ss Anatomy of Epeira Auditory and Olfactory Onaere of. Beuers: Anatomy of Pentastomum Protelis .. .. Pycnogonids of the Faeroe Channel Development of Limulus 6. Crustacea. oe Xili PAGE aekante2225 no Letien @) asa oe Teas 500 . Part 4 558 © Bhar 558 Sayer sy 559 Part 5 741 .. Part 6 884 oi Natio 885 sai uns 885 Ra, iss 886 Belin. $5 887 56 888 ae oad 888 Growth of Carapace of Crustacea and of Shell of Mollusca Part1 34 Spermatogenesis of Podophthalmate Crustacea .. AGRIC ISOC «00 00 00,0 New Host for Cirolana concharum ie Copepoda Entoparasitic in Compound Ascidians. . Anatomy and Physiology of Sacculina .. Sexual Characters of Limulus .. .. Ewidence of a Protozoea Stage in Crab Development... Gastric Mill of Decapods .. .. Spermatogenesis in Hedriophthalmate Gristacea LL GWEP Of IUGCH NON 3 00 00 nS ‘Challenger’ Copepoda.. .. «+ « o« Longipedina Pagurti .. .. . « «o OndiGRe co on 00 Deep-Sea Crustacea .. 1. «6 «2 0 Sexual Colour- Variation in Cructeone. co. co Observations on Tanais Girstedi.. .. «. New and Rare French Crustacea., .. Stomach of Podophthalmate Crustacea Significance of the Larval Skin in Decapods New or Rare Crustacea 20 o0 Rate of Development of Conair ines Bis 9 Chuettiqnaar ° lisa@etlis 20 00 00 00 60 The Cryptoniscide .. . sausesiaaes yee Antennary Gland of Cy theriate bo. Gory 6 ‘Challenger’ Cirripedia .. .. Vermes. Classification of the Phyllodoceide .. .. Anatomy of Polynoina., .. .. « Spadella Marioni.. .. 1 oo New Forms of Thalassema.. .. Spermatogenesis in the Nemertinea .. Development of Trematoda-., .. .. ; Fe 50 Piney 50 2 51 : 3 51 0 51 Part 2 226 5 226 Aig 227 228 Part 3 375 AO aS 376 Fr 377 ” 377 ees 377 . Part 4 560 = 561 yaeaeeas 562 . Part 5 742 aes 744 etnies 744 .- Part 6 888 Fey oy 889 jap ose 889 hae 890 se 890 » Partl 53 ates 54 9 4 ”? 333) . 55 XIV CONTENTS. PAGE Simondsia paradowa 1. +s «1 +e oe oe ee os Partl 58 Monograph of the Melicertide «1 ss se ee ee eng 58 Observations on the Cy of Stephanoceros Eichhornii. (Plate V. Figs. 1-3) .. .. .. « « Part 2 169 Annelid Commensal witha Coral.. .. .. Ran Aes lass 204 Structure and Division of Ctenodrilus pomesties au | 60 5p 229 Manayunkia speciosa .. .. « Cot: Money do wooden 6) 231 Parasitic Nematode of the Common Onin eine eat 232 New Myzostomata «ss ee ne wee ne weg 232 Bucephalus and Gasterostomum .. ++ ++ se ee eg 232 Development of Dendrocelum lacteum .. SOMEM ON Waco! iss 234 Rotatoria of Giessen «1 66 ee es wean we gg 235 Rotifer within an Acanthocystis .. «+ se 66 se +e 238 Development of Worm Larve .. «1 « «+ «+ «+ Part 3 378 Excretory Apparatus of Hirudinea .. .» ss oe es 379 Function of Pigment of Hirudinea «1 46 vu we we gg 379 Otocysts of Arenicola grubu om 880 Manayunkia speciosa .. 6s oe eee egg 380 Life-history of Thalassema.. .. os 7 381 Spermatogenesis and Fecundation in ligase pagetacetaPs ~) 382 Structure of Derostoma Benedent.. «1 «1 «6 + 08 49 383 Opisthotrema, a New Trematode .. 2. +1 +6 se oe ogg 384 Polycladidea.. . oO) oo: OO! «rp 385 Early Stages in the Developmiat 9 Balanoglsss an 388 New Rotatoria .. . : oe MKOCN UabGyy on) akeeD 888 Nervous System of eames ee de -- . Part4 564 Cerebrum of Eunice harassii, and sta Relations to the Hypodermis. si 9 ae se ee) wel ev foe Pee incl | sy 964 Varieties of Byaneiasdeta CURIS 55 oF 95 565 Ovum and its Fertilization (in Ascaris) “ 565 Spermatogenesis in Ascaris megalocephala .. .1 «6 «+. 45 567 Spermatogenesis in Ascaris megalocephala .. .« «+ +. 4 569 Nematoids of Sheeps’ Lungs.. .. +» «6 «6 ce os 455 569 Free-living Nematodes .. 1. «+ «+ 0 4 48 06 45 570 Trichina and Trichinosis .. 1. .. 0 oF «8 oF 45 570 Cystic Stages of Teniade .. .. aah “ete ue ee es O71 Anatomy and Development of Prematoda o0 oe 5 571 Worm Fauna of Madeira Leen ded Pate. GEE Sve coe 573 Ngan Sa@egs Of IROSHGPso 00 100 00 00h 973 New Type of Hirudinea .. 41 se te we -- Part 5 744 Structure of the Branchie in Shommioscr 3G) “ob od ogy 745 Structure and Development of Fresh-water Dendrocela .. ,, 746 Glassification of the Rotifera). <2 ss es) es oly Iie IPqag i IHU 000 sisit,si HG EY Head-kidney of Polygordius 50. 00 1 6D) 90 OD) oo 892 Nervous System of the Archiannelid@ .. 1. «6 1 o 4) 893 ALE OMO) OF GG JORGUTAD 55 60 00 of op oo co 893 External Morphology of the Leech .. « . ban 896 Action of a Secretion obtained from the Medicinal ieee on the Coagulation of the Blood .. «1 12 se oF oF 896 Organization of Echinorhynchi .. .. ab gy 897 CONTENTS. KV PAGE Biatozoic Worms > yas) ae) cep 1 -o, ee) emesis EOXtG SUS Nervous System of Trematodes .. .. 30 5 898 Rhabdocela from the Depths of the Lake ap Geneva Be poe 898 Physiology of a Green Planarian.. .. 35 899 Worthington Smith on Diseases of Field ae) benean Orvis a 935 Echinodermata. Histology of Echinodermata...» «+ « « « « Partl 60 Nervous System of Holothurians .. ss «1 «+ «6 oF 4 62 Vascular System of Echinoderms.. «6 «6 «+ «6 «+ 4% 63 Echinoderm Morphology «+s se ve we we we Part 3 389 Development of Comatula .. «6 «5 66 «6 oe ee og 389 Pharynz of an unknown Holothurian .. .. «1 5 +8 59 390 Nervous System of the Crinoidea ae [0 901 Development of the Germinal Layers of ennecernae .. «. Part4 573 New Genus of Echinoids .. «6 21 ++ 66 0 eg 574 Revision of the Genus Oreaster .. .. +» ++ ee te oy 574 Organization of Adult Comatulide ., «+ +» « «+ 5 575 Constitution of Echinoderms JOE Ney haa, bo AU ONO Pourtalesia .. act Sao meicee. CaouN ecb ieee aT 751 Anatomy of ihe Coieatte oc es we OL Notes on the Structural Sienaatare ee the “Sings of Echinoidea. (Cidaride.) es XIII. . ee ariOMsto Structure of Echinoderms .. .. + 50-00» yooN tp 900 Nervous System of Antedon rosaceus .. .. «+ «+ 4 4 901 Nervous System of Crinoidea ... Het. gsm teh 902 Asteroidea of the Norwegian North Se, 1 Eapetition els vai8 a 903 Mimaster,anew Asterid .. .. « aoe stosa boom alan 903 Amphicyclus, a new Holothurian .. .. «1 «+ 08 8 ys 903 Cuvierian Organs of the Cotton-spinner «1 + we we oy 904 Ccelenterata. Commensalism between a Fish and a Medusa .. .. . Partl 35 Nervous System of Porpita .. .. +6 «+ «5 24 08 59 64 Bermudan Medusa .. « . CU cans Sorel, ten Commensalism between a Fish aid a Medusa Pee ae bart 2) 204 Annelid Commensal with a Coral tion Ba 5 204 New Alcyonarians, Gorgonids, and Pennabialds of the Norwegian Seas Jouiscee AeaGndetic o Nop | A0do Wop alco, Okrp 239 Origin of Coral Reefs 2. .. «5 + 06 «2 ef 22 9 240 Porpitide and Velellide 1. ss 0» «6 06 6 «8 59 241 Mesenterial Filaments of Alcyonaria .. .. .» «. «. Part3 390 Anatomy of Peachia hastata .. ss oe oe we wos 391 Ephyre of Cotylorhiza and Rhizostoma .. «. «. «+ 9 391 Anatomy of Campanularide eu aa Wee ae oe bart of: Structure of the Velellide .. 1. .« «2 «8 «8 oF 9 576 Actinie of the Bay of Naples .. «1 «2 «1 2» «8 O77 Notestonn cds ae ee te eee oem kart ooo Revision of the Maireporaria ate eet set eee <5 759 xvl CONTENTS. Porifera. Alleged new Type of Sponge 6a bu 00 Biology and Anatomy of Clione .. .. New Siliceous Sponges from the Congo Honan Physiology of Gemmuules of Spongilide .. .. European Fresh-water Sponges .. .. New Genus of Sponges .. Calcisponges of the * Challenger ” Biyactiean Australian Monactinellida .. +s» «ss s+ Japanese Lithistide .. . a> Go 00 Fossil Sponges in the British icon 00 | 66 Vosmaer’s Manual of the Sponges 00 New Gastreades from the Deep Sea .. .. Siliceous Spicules of Sponges Fresh-water Sponges and the Pollution: of Riveronater Vosmaer’s Sponges noo Fresh-water Sponges .. «+ Protozoa. Parasitic Infusoria oo . «2 New Infusoria .. . Relationship of the Hageliata to une ae Winsor Transformation of Flagellata into ee vie Stein’s ‘ Infusionsthiere? = 6. se aw Cilto-Flagellata .. New Choano-Flagellata Anatomy of Sticholonche zanclea ob on Studies on the Foraminifera ook wn 00 Development of Stylorhynchus .. Trichocysts of Paramecium 00 Biitschli’s ‘ Protozoa’ New Infusoria ; Reproduction in Leoielasins feast Orders of the Radiolaria Bohemian Nebelide .. 50 Action of Tannin on Infusoria .. ae Nucleus and Nuclear Division in Protozoa New Infusoria Stentor ceruleus 20 Chlorophyll-corpuscles of some ricony on Life-history of Clathrulina elegans Aberrant Sporozoon Noctilucide .. .. .. eo oo eo eo eo eo eo ec ee ee eo On Protospongia (soeeaieaten a new Consened Injusrin (Figs. 85 and 86) .. .. : Morphology and Anatomy of Ciliated Oy auR Trichomonas vaginalis .. oc a0 Acanthometra hemicompressa Orbulina universa .. 90°. a0 Nuclear Division in Ba osrhaninn eichhornit .. New Infusoria .. eo ee eo eo oe PAGE eRaxt loo: 5 65 ac Ness 66 . Part 2 241 th 242 5 243 Part 3 392 5 394 a 395 55 396 Oat es 397 . Part 5 756 5 757 757 Part 6 904 » L004 Part l 67 »» 68 ” 68 » 369 ” 70 ” 72 ” 73 9 73 age ” 74 157 Part 2 243 “3 244. i 245 “ 246 5 247 305 Part 3 398 5 401 35 401 Fe 401 Pa 402 % 403 7; 403 Part 4 530 ey rT 5 579 » 979 ns 579 580 CONTENTS. XVii PAGE Parasitic Peridinian wows wy ws te a ae, Part 5 759 Observations on Flagellata .. 1. ++ «5 06 28 4s 145 759 Geometry of Radiolaria «1 ss se ue te tet 759 Polythalamian from a Saline Pond dhe Wencie c0n4) ch ease wat) 760 Nuclear Division in Actinospherium eichhornii .. 1 «+ 455 761 Parasite of the Wall of the Intestine v WNC 1EOFSA 6a 50 762 Sutherlandshire‘ Fozoon”” .. «. Poe eee, Owen 763 Nuclei of Infusoria .. Ce a) eke eartson. 90 ae New Infusor p= Ciatictere abantioentatl Kaas! — 55 905 New Fresh-water Infusoria 60 sin | Oe: (96 4600, Lage ssp 907 Life-history of Stentor ceruleus nih WROLe Aho hAb Om omane 907 New Rhizopods and Vorticelle .. .» . « «© « 4 908 ‘ Challenger’ Foraminifera BS eOG: 1omDO | ROG: (ROE: Sonne 909 Copulation in Difflugia globulosa .. «1 +1 ws we 911 Development of Stylorhynchus longicollis .. «1 «» «+ 45 912 Flagellated Organisms in Blood of Animals Boi oe hee 913 Parasitic Proteromonadid@ .. .. s» «ss «+ «F oF 49 913 Bacterioidomonas sporifera ae a0 | ip 934 Influence of Gravitation on the iene of Gann domonas and Euglena 14 11 we ws $5 938 BOTANY. A.—GENERAL, including Embryology and Histology of the Phanerogamia, Relations of Protoplasm and Cell-wall in the Vegetable Cell. Part 1 75 Intercellular Connection of Protoplasts .. «+ « «+ 4 76 Polyembryony of Trifolium pratense . nine gecan teeth ness 76 Mechanical Structure of Pollen-grains 50 0D oo gh 76 Fertilization of Philodendron .. ss +» ee tn 6 TT Fertilization of the Prickly Pear.. .. .» « cee Pa 77 Annual Development of Bast 1. «» «1 «+ Te Lenticels and the mode of their replacement in some weootly tissues a Es oe ae Se sions, (aus asta cea Teed oss 78 Gum-cells of Cereals Sol hdoe abi ods Boll ap x 78 Nucleus in Amylaceous Wood-cells .. «1 08 « 5 79 Peculiar Stomata in Conifere@ .. .» +» ae oe wag 79 IBOORGETS co on ob a0 cd Go 00 aC % 79 Steve-tubes of Cucurbita ape Perrone Mcietadkaclela (= sinus Mitel aest oll Ja's5 81 Spines of the Aurantiacee .. .. «6 es we we wg 81 Tubers of Myrmecodia echinata .. .. 50g 81 Chlorophyll-grains, their Chemical, Mor, phological, and Biological Nature .. . ais os we ie Pa 81 Mechanism of the Splitting of enunee O° 5 82 Aerial Vegetative Organs of Orchidee in relation to Rap Habitat and Climate... .. « 30 *H 83 Assimilation of Carbonic Acid by pentoniaen sonich ne not contain Chlorophyll .. .. 9000. ¢p 83 Artificial Influences on Internal Cutises of Gronth S8.oP BD <5 83 Absorption of Food by the Leaves of Drosera.» +» «+ 4 83 Mechanical Action of Light on Plants op «OO . 84 Action of the Amount of Heat and of Maximum Tae. perature on the Opening of Flowers APY Reco aiaeeo. TaLOom ale 85 Ser. 2.—Vot. IV. b Xvi CONTENTS. Behaviour of Vegetable Tissues towards Gases .. .. «. Influence of External Pressure on the Absorption of Water OY LEGO sn dco oc ; eye Contrivances for the Erect Habit of es and Vafiaices of Transpiration on the Absorption of Water.. : Sap oo “oth, /bos Mook on Solid Ppeants m ve Cig aii wi 20 30 Movement of Sap in Plants in the Trees : : Exudation from Flowers in Relation to Honey-dew .. Latex of the Euphorbiacee .. 3 Crystalloids in Trophoplasts and Chromeplats of Angio SPErMS ne. ae 40 , Formation and Resngatiinn of Cystoliths Bae PN ae Un Functions of Organic Acids in Plants.. .. ar Formation of Ferments in the Cells of ie Pins 3c Poulsen’s Botanical Micro-Chemistry . es Living and Dead Protoplasm Aldehydic Nature of Protoplasm bo 90 00 Embryo-sac and Endosperm of iar Boe 0G: 'do Constitution of Albumin... 56% Ibe. Fe Fertilization of Sarracenia uma Gil o5 Ab Pe Sexual Relations in Monecious and Diccious Plants 30 Corpuscula of Gymnosperms .. .. Comparative Structure of the Aerial oui slibtenr raneous Stem of Dicotyledons .. . Function of Root and Stem in “Diactaieties ee Mone cotyledons.. .. soda cexolal syaice eco autorsadecisObamess Suberin of the Cork- ay oc Influence of Pressure on the Groen and Str ctu é of Bap ke Relation of Transpiration to Internal Processes of Growth Easily Oxidizable Constituents of Plants .. Action of Light on the Elimination of Oxygen .. Red Pigment of Flowering Plants .. . 00 > 00 Coloured Roots and other Coloured Parts of Plants 50 Starch in the Root 66 00 any) dow as Proteids as Reserve-Food Materials 90 Leucoplastids ZOt) Hopes) Cosei-aner oop a oae ane Cleistogamous Flowers... ». 50 Cultivation of Plants in Beosmoasatag Swinton a Or ae Matter .. Sd onl Wy aGe. ab Sow ace So Disease of the Werment JHUNP om foo bo Fide aD Flora of Spitzbergen .. .. .. «« Continuity of Protoplasm .. ts and Dead Pr flag x 90 Occurrence of Protoplasm in Intercellular Gocco Division of the Cell-nucleus .. 1. 65 ee ie Apical Cell of Phanerogams.. .. «+ +. «1 ss 0 Nettle-fibre .. .. 30 Laticiferous Tissue of Manihot Glaziovii (Cearé Rubber) 30 Laticiferous Tissue of Hevea spruceana ba 88. 00 Part 1 PAGE 85 85 91 : Dei 2 250 250 250 251 251 251 251 252 253 254 254 254 255 257 _ 257 259 259 260 260 260 260 260 261 404 405 406 406 407 408 408 409 409 CONTENTS. Development of Root-hairs .. oo. ++ «+ Symmetry of Adventitious Roots., .. aD Penetration of branches of the Blackberry Aili the Soil Circumnutation and Twining of Stems Vegetable Acids and their Effect in Producing Fin Wiley ee Metastasis and Transformation of Energy in Plants.. .. Action of the different Rays of Light on the Elimination v Oxygen .. . a9, 00 00a Movements caused a Chemin Agents Direct Observation of the Movement of Water in Pints Rheotropism .. .. : Bee aant, yess Transpiration- Onan m Wendy Phage Origin and Morphology a ae ae niet) Allied Bodies 00 aD 60, 00,7 00 00° a0 Spectrum of Chlor Benaicie Portion of the Spectrum that Decomposes Gucion DRoasFe Chlorophyll in Cuscuta 00 oo BG Work Performed by Chlorophy a. Spherocrystals Spherocrystals of Basra hagas 30 Calcium Oxalate in Bark ° Homology of the Reproductive Ontia m Pane ogams nd Vascular Cryptogams .. Influence of Light and Heat on fhe Gemenition of Seeds .. Origin of the Placenta in the Alsinee ES Gemme of Aulacomnion palustre .. . 0 Relation between Increase and Segmentation @ Cells . Development of Starch-grains in the Laticiferous Cells a the Euphorbiacee@ 1. «eos ee ve wwe Constitution of Chlorophyll .. .» as Cellulose accompanying the Formation of Gristals Middle Lamella of the Cell-wall .. . Intercellular Spaces between the ieee Cells as tera Contents of Sieve-tubes.. aoe 0° oo Organs of Secretion in the ebracatenaae Tracheids of Gymnosperms .. Apparatus in Leaves for Reflecting Pa. Swellings in the Roots of Papilionacee Origin of Adventitious Roots in Dicotyledons Crystals of Silex in the Vascular Bundles.. .. Effect of Heat on the Growth of Plants .. .. Curvature of Roots Torsion as a Cause of the Diur ral poston of Foliar 01 rgams Assimilative Power of Leaves 0 Quantitative Relation between Ansoration’ of Light fend Assimilation .. Causes which Modify the oer ‘Action of TEE on gens Respiration of Leaves in Darkness o0 Movements of the Sap in the Root-tubers of tie Dahlia Absorption of Water by the Capitulum of ee Measurement of Turgidity ., .. + HAY aoc D X1x PAGE Part 3 409 . Part 4 ” 2 409 410 410 410 411 411 412 413 413 414 415 415 415 415 415 416 416 416 581 583 583 o8t 584 584 O84 585 585 586 586 586 587 587 588 588 588 988 589 589 589 590 590 o91 591 391 592 XX CONTENTS. PAGE Continuity of Protoplusm .. .. .. « «+ «s « PartS 763 » = Re Se aes Wes Me toe). 55 764 Osmotic Power of Living Protoplasm.. .. 1.2 «1 «+ 764 Structuneof Pollen-graims) Ve ts. ae se ee see 5y 764 Seeds of Abrus precatorius .. .. oo. 6p 764 Comparative Anatomy of Cotyledons gd Fititosnernie Bike Ws 765 Underground Germination of Isopyrum thalictroides .. 4, 766 Stomata of Pandanacee 4. 4. wee Ba OME cr 766 Changes in the Gland-cells of Dionea itso during Secretion .. FTL eee eee eis = 2; 766 Septal Glands of lonocctylaicne® Bree Merrie 50. ye Oc loamy 767 Secretory System of Composite .. .. «ss «+ « «+ 4 767 Chemical Constituents of Plants s. 1. «« «2 «+ « 4) 768 SUMUCHRG Of JLGUIERES 59 oo co 09 90 of op oF 769 Transparent Dots in Leaves i POUL a oba8 oem 769 Secretory System of the Root and Sie D2 ie MRE 55 770 Anatomical Structure of the Root coe, acriody. bo 1M criaalie Oey 71 Growth of Roots .. .. oo | Oy 772 Growth in length of Dentin sand RAT URES Penta: 9 0b 772 Geotropism and Hydrotropism of Roots .. .» «.. «+ 45 7173 Water-glands and Nectaries 7 emits MAR ees | 5 7173 Folds of Cellulose in the Epidermis of ‘Petals Bo. OG. | soa 773 Anatomical Structure of Cork-woods .. .. .. « «+ 45, 73 “ Filkform Apparatus” in Viscum album .. 1. «2 «2 4 773 ZACHiOnN Of Heat upon WWegeLation «a Wanye Sele eel oe 5, 774 feelations of Heat to the Sexes of Flowers .. .. 9 775 Influence of Light on the Structure of Leaves of Allium ursinum .. ig ek See 775 Effect of Light a Shade on Ry Evaetiones cas oye tice Garo wes 7795 GRA Of MWVOIEP Gp IIS gn on SS ‘5 775 Movement of Water in the Wood.. .. .. .. 2 « 776 Measurement of Transpiration .. 1. «2 «1 «1 -9 WU Exhalation of Ozone by Flowering Plants .. .. .. «. 4 717 Acids in the Cell-sap .. Beton Sete. 5 1717 New Colouring Substance fe Chloropyt vin ED. aR 778 Crysnoicne Chilorgpailics oo 00 eo 00 06 00 oo 778 Crapialis crea) CirmsgllGsG8 oo 06 oo 00 50 09 00 35 778 Spherocrystals .. . PBL Cen St eee Ps 779 Formation and ascan tine of Cystoliths nots sah Morn Wedocn) 2) oh 779 Dewlayoingos Of LGV oo ag 6000 779 New Vegetable Pigment ig ora SANSA eee rae Rose 3 780 Fish caught by Utricularia .. .. ale nora 5 781 Observations on Vegetable and Animal Cells ve) we art 6 (914 Structure and Division of the Nucleus of op 00. , 00 915 Formation of Endosperm in Daphne .. .. Ka es 915 Method of Bursting of Sporangia and Poles ; 0 916 Pollen from Funereal Garlands found in an Pouption Tomb Le oa gir 916 Swelling Proper tes of Vegetable Galeneninene Sahota Oo 1 GS 916 Hipider min lassie -Of thew hOOt) “ch |v.) a. qh eee ee OCT Lenticels ae eee ne eee cone 917 CONTENTS. Xxi PAGE (Raps Of DRACO SUGGES “eb 66 60 on 00 co get LEC )Ir/ Structure and Growth of Palms .. .. .. .» «+ «= 4 917 Honeneqland siof Crucrfen iyi a0) simian iss 918 Resin-deposits .. . : Ge Laoag. BO: | op 918 Distribution of Teadbgoatiattalls mt) the Plant Ee 00 918 Transpiration of Plants in the Tropics .. «1 +» «0 455 919 Chemical Phenomena of the Assimilation of Plants Bo!) MBL) rep 919 Histo-Chemistry of Plants Soa SS Gr Nos Bon? wep 919 IYO COORG DON oo po 66 00 00 80° oo on Og 920 Lime and Magnesia in Plants .. .. SADA ae mein ORs 920 Easily Oxidizable Substances in Plant Sap So weReEh PRaCoeE nee 921 Action of Nitrous Oxide on Vegetation ys re 921 Silicification of Organs 60 gp 921 Influence of Solar Rays on the Te iyperitre of Tio sete es) 921 Thermic Constants in Plants .. . . 60,00 9 921 - Chemical Changes in their Relation to Micro- onpeGis eth Mery 922 Comparative Morphology of the Leaf in Vascular a gams and Gymnosperms .... 3 922 Worthington Smith on Diseases of Field oe Gurcen Cr a8 $5 935 B.—CryYPTOGAMIA. Cryptogamia Vascularia. ; Deda: Of HMGSUE, 50. 00 00 oo cc oo oo Jeti ll BB) Classificatzonof; Opiioglossacee) ss ee ee) ae ee) os 92 Surnonime Of JEAMMOTOSTHONUB co co 06 06 00 08 92 Fructification of Fossil Ferns... .. .. .. =. «. Part 2 261 Prothallium of Struthiopteris cea Sater ae su tae h eae 262 Stigmaria .. « bi aero . Ban 3 417 Homology of the Repr aatnetine Or “ete im Phianeroqans and Vesculem CPOjROGoRS 55 o5 co 06 so oo oo Jenn Zt Syl Origin of Roots in Ferns 6 092 Munograph of Isoete 35 093 Systematic Position of liege ere, ‘Sigillaria 7, ard Stigmaria.. .. pat Sr ed Ee ane ath 593 Anatomy of Vascular Cryptogens 00. 0o- ao co oo Jee Fell Fertilization of Azolla .. 5 781 Comparative Morphology of tel hee mm vacua Oe togams and Gymnosperms bc no og «oS EL GDA Apex of the Leaf in Osmunda and Te a 56 923 Rabenhorst’s Cryptogamic Flora of Germany is Vascular Cryptogams) ft ei Nees ee een ® Bo 9 924 Muscinee. Structure and Development of certain Spores .. .. .. Partl 93 Mucilage-Organs of Marchantiacee .. .. .. .. « Part2 262 Cephalozia .. .. poh Lah) sobs G04) op. Joo os eta, Guly/ Variations in Sekine BU) G0. unos Mech sob) abe. aoe enbenee ye Male Inflorescence of Mosses .. 5 oo oo Letty &) ‘7ASI Lesquereux and James’s Mosses of Non th Vee HOG rope Woe es 782 Braithwaite’s British Moss Flora soy op oa an oo Leer ) Be: TE oHes JS 7090 HOSES 56 ed. Go. be on. ne) be 924 Xxll CONTENTS. Characee. PAGE Characee of the Argentine Republic . Part 2 263 American Species of Tolypetta eas 263 Cell-division of Characee . Part 6 925 Fungi. Alkaloids and other Substances extracted from Fungi -. Partl 94 Development of Ascomycetes 5) 94 Conidia of Peronospora as 95 LAOS VOR INGRUUT UM = 00 00st 5 95 Chytridiacee c ” 96 Phoma Gentiane, a new 5 BB aeiie jing = 96 Chrysomyxa albida 5 96 Physoderma .. 72 97 Bacilli of Tubercle 5 98 Microbia of Marine Fish 9 98 Physiology and Morphology v Allesiif Fer nant >» 98 Alcoholic Ferments .. . Foe ae + 99 Magnin’s Bacteria 9p 99 Bicentenary of Bacteria + 144 Rabenhorst’s Cryptogamic Flora °f Ge many y Ging) Part 2 264 JEM ~~ on 50. 50 ATM y Seah Ger safest ahs 264 Graphiola =. ne 5 264 Pourridié of the Vine... * 266 Oospores of the Grape Mould cp 266 Pleospora gummipara .. 0 266 Schizomycetes = 266 Fecal Bacteria ; ey Aa] Cie. es 267 Influence of Osram ee High Pressure on Bacillus anthracis .. : Pa aA ae Bee iss 267 Bacteria in the Hage Aigerse 66 op 268 Bacillus of “ Rouget” 55 268 Living Bacilli in the Cells of Valisnen aa rs 268 Simulation of the Tubercular Bacillus by Cr Tsaline ors - 269 Cultivation of Bacteria.. Bee ocala 2 30 269 Reduction of Nitrates by Recents AG 6 269 Lamelle of the Agaricini j Part 3 418 Formation of Gum in Trees . on ee wes 419 Attraction of Insects by Phallus and Coprir mus .. Fa 420 Development of Ascomycetes 5 _ 420 Fungi Parasitic on Forest Trees .. Ac a 421 Puccinia graminis on Mahonia aquifolium .. 423 Polystigma rubrum 2. ws Bs 423 New Synchytrium .. is 423 Pathogenous Mucorini, and the Myeoss of Rabbits panic by them 30 00 » 424 Micrococci of Pisiimonil pica ha ae ier < 425 Bacteria of the Cattle Deter 426 Passage of Charbon-bacteria into the Mi ilk of Animate Infected with Charbon ; oh Meare ade 427 Comparative Poisonous Action of Metals on Beier 30 427 CONTENTS, XXlil PAGE Micro-organisms in Soils .. .. . - . Part 3 428 Bacteria and Microscopical Algzx on the Surface of Coins in Currency . she. (Cash Gtssimy cater Sorat aap Qepstietr creme seman eS 428 THOS Sonn ame ae MOM Ia Manco RNcn ison. hc) Bae. dep 430 Yeast Ferments .. AE NOD MLO, ose Mane HOt: to ei Ure 431 Action of Cold on beenies 60. od 1) 432 On some appearances in the Blood of iventeinaned Unters with reference to the occurrence of Bacteria therein .. Part 4 525 Sexual Reproduction in Fungi .. +. 45 00 ene gg 594 Life-history of Aicidium bellidis D.C. Baer Peeper 595 Structure and Affinity of Spheria inocu CHNHA 0, BD tan, be 595 Spheroplea .. .. Bot DDS Godin hb aebe mice UB 595 New Parasite on the Silver Pir aoe Rca caan ties 995 Micrococcus prodigiosus within the Shell Ge an Ths Be, AG eae 596 Photogenous Micrococcus ws) © os ee gp 096 Respiration of Saccharomyces .. .» «1 «ss se is 9 596 eens OF GROKIRB 30 00 209000 xe 3 d96 Virus of Anthraz.. .. apes 9 598 Attenuation of Vir us in (Cutivations be Garner eed DERG ere See Ni aibgemron aimee! Iran se Man) Mea na nok eneliaaes 999 IBOWB 55 a0 stslles Cathay atin awit ss 55 600 Bacteria in Canals ana Chines Saf NGL CWE) SROMAT AEM ST > igs 600 Bacteria from Coloured Fishes’ Eggs .. .. 1. +» «+ 55 601 Bacteria connected genetically with Algw .. 1. 44 +e 5 601 Action of Oxygen on Low Organisms..© .. 1. «0. «455 603 Biology of the Myxomycetes 00 56 603 Supposed a and Disengagement 71 Mitr hen aay LEGA a0 00 regs oo oo dete by 7S Fungus Parasitic on Dr deanna sina baslyshol i cialis tone Ue dete nnee ema 783 WACONOS PORE, acon vema re cebel CNL eee. seo ae ube seat aes 3 783 Vine Mildew... .. sph (peje tole aS RVeRe ok loka a tfak ees aattees aS 783 New Theory of Henmientation Anphedat Money Luda eG a 784 Microbes in Human Saliva .. 6. ~.. 1. 2 «2 «1 gy 784 SMGIRGENE OFF HUMUR oo do. 40 ao 631-8065 bo 00 x 786 AGRE? Of © AHORWMD”’o5 00 60 0000'S 00s, 35 786 JROGHS Of WOE 00 5086 00g 786 JRO oo op SE CM Co era deOoe ere eens 787 Etiology of TiabeneHots oo Ae ere a cE er, 7187 Bacteria and Minute Alge on Papet fone eae. Yon \ Taeenu en 787 Grove’s Synopsis of the Bacteria and Yeast Fungi .. .. 4, 7187 Protochytrium Spirogyre, a New Myxomycete (?) .. . 788 Description and Life-history of a New ge Milowia IUUDC Cm Clalaite PNGB) Surtees) eet -len lee) ue ype altGn S450 JOYCE JHURG 25 05 60 60. on 40 00 00 op 925 Parasitic Hymenomycetes ..- .. sel luaas ena oie te 925 Mode of Bursting of the Asci in the Sor tant (QB oo \ac- | oo 926 Actinomyces... .. Ao TN has ea riceas 926 Rhizomyxa, a vee Ph meee Pty 3 3 927 Effect of Light on the Cell-division of Chacon OMYCES.. -- 55 928 Behaviour of Blood-corpuscles to Pathogenouws Micro- RIOTS 56 lt b6 | oo Ge obtilaeas Iho. ol) 6000) sp 928 XXIV CONTENTS. Micrococei of Pneumonia .. ac Micro-orgunism of Zoogleic Tuber Act ac Microbe of Typhoid Fever of Man Bacillus of Cholera and its Culture 5 Influence of Culture Fluids and Medicinal Recent on the Growth and Development of Bacillus Tuberculosis .. Chemical Properties of Bacillus subtilis . Supposed Identity of Hay Bacteria and those of Cattle Dis. temper oo . 0 4G) een 0 Bacterioidomonas sporifer. eye Rabenhorst’s Cryptogamie Flora of aanan (Fungi) Worthington Smith on Diseases of Field and Garden Crops..- Noy tetera san ke WN eye Myxomycetes with Poeuto-plasmotia 20 “* Sewage Fungus” 4 bp. 90 Lichenes. Cephalodia of Lichens .. Lichens from the Philippines Cephalodia of Lichens .. Thallus of Lecanora Hypnum Substratum of Lichens . Hymenolichenes .. . bore Dara ete Relations of Lichens to the Ntheostee € Alge. Symbiosis of Alye and Animals... .. . Relationship of the Flagellata to Alge and Taflsoria ia Transformation of Flagellata into Alga-like Organisms .. Protoplasmic Continuity in the Floridee .. .. Distribution of Alga in the Bay u Naples... Alge of Bohemia .. 50 3 Fossil Alga New Genera of Alje 0 Polymorphism of the Phijcochvomacen: Reproduction of Ulva .. 40 20 Relationship between Cladophora an Rhieocloniuin 00 Classification of Confervoideee =: Action of Tannin on Fresh-water Alga New Species of Bulbochate .. New Genus of Oscillariee -.. Vaucherie of Montevideo Gongrosira E Phyllosiphon Arisari Occurrence of Crystals of Gy ypsum in He Despre List of Desmidiee found in gatherings made in the neighbour- hood of Lake Windermere during 1883. ec! VY. ik 4-7) : On the For riton eh Cane f Cells mn Tee genus ron y- siphonia. (Plate VI.) roads ‘ PAGE . Part 6 929 $i 929 3 930 = 930 ay ag32 ss 933 53 933 a 934 a 935 a 935 e 935 " 937 . Part 1 100 eer Be ON . Part 4 604 mis |S 605 ap lenny) 7S) Wen is 790 . Part 6 936 5 letie il Se 99 68 9 69 tor R102 = toe ‘ 102 a 102 aos Jo" 105 5 106 » 106 - 106 Pe 107 = 107 se eel OT, z5 107 5 108 55 108 . Part 2 192 CONTENTS. Rabenhorst’s Cryptogamic Flora z Germany (Alg@).. Distribution of Seaweeds .. . 6 BOUL. emo. .a0 Cystoseire of the ee zi mee BORER 0 ENO.! Loo wt Polysiphonia ., «» oc Pe LOO OCOD o0° 05. Ngai do. a0 00 06” 00 G0 Resting-spores of Mie SOMA OO ab k e0G, a0 Hybridism in the Conjugate eer New Genera of Chroococcacee and eaveleee 50-90 Chroolepus umbrinum .. : Constant Production of Oxygen th Yy ie Action of Sunlight on Protococcus pluvialis .. .. oH 90 oo! 90 Chromatophores of Marine Diatoms Division of Synedra Una Arctic Diatoms Pelagic Diatoms of the Baltic Diatoms of Lake Bracciano .. ob Gbb On Certain Filaments observed in Surirella ifhons: (Figs. 49 and 50) Bacteria and ieerasear steel re on We sosfinae of “Coins in currency Fertilization of Cutleria Endoclonium polymorphum.. Godlewskia, anew Genus of Cr ptoplucen a Sexuality in Zygnemacee .. .. un ws Movements of the Oscillariee Alveoli of Diatoms Researches on the Str settee oi the Gelanalle of Diners (Plates VIIT. and IX.) . oe seni Pesce ct Systematic Position of Wilenene GCN, OTN Ede ak. /DOCEN Ci Newly found Antheridia of Floridee New Unicellular Alge .. : Structure of Diatoms Belgian Diatoms .. Diatomacee from the ela of Saati, a Researches on the Structure of the Cell-walls a Dialers (continued). (Plates [X., X., and XI, and Fig. 119) .. Bacteria and Minute Alge on Paper Money Fresh-water Pheospore od . MOSHE co co 00 on. oc New Chromophyton .. Wolle’s Desmids of the United Sis. Of New Diatoms—Diatoms from Stomachs of apenas Oysters oe Structure of bistons Ee Researches on the Structure of the Gieaeds of Tete — Eupodiscus (Fig. 144) : On some Photographs a Broken Danton ation taken by Lamplight .. Aen Sates | iakiige cia Stes Algae of the Red Sea Afghanistan Alge Conjugate . Part 2 Part 5 -. Part 6 XXKV PAGE 270 270 271 271 271 272 2738 273 273 273 274 275 277 277 217 352 XXV1 CONTENTS. PAGE Floating Rioularice .. 4. 15 06 ee we nee Part 6 937 [Spohacel rir ve atee new es ene ieso Proce T- 937 “ Sewage Fungus” .. aC Aimee nC Cue Ose Fp 937 Growth of the Thallus of Ontos sation scapes 06 937 Influence of Gravitation on the Movements of Onennae domonas and Euglena .. se +e ee we we we gy 938 Chytridiacee .. .. (gta ee eer Maret” Melani Ica Mtscon ate) STs 938 Cooke’s Fresh-water Vite lel es TNR Se Wels ss 939 Alge in Solutions of Magnesia and of apa Soke aD eee 939 Confusion between Species of Grammatophora .. +1 « 9 939 Depth at which Marine Diatoms can euist.. 1. +1 «5 45 939 Diatoms of Franz-Josef’s Land... .. 66) 00 940 Structure of Diatoms from Jens sf Cenenk Stone” at ely 940 Structure of the Diatom Shell 4. se ae ee wee 3 943 MICROSCOPY. a. Instruments, Accessories, &c. On the Mode of Vision with ancuge v Wide Aperture (Figs. 1-7) «. - . 5 oo oo oo Jemde il AD “ Giant Electric Miieroseonee: ae i 109 Aylward’s Rotating and Swinging Tail-picce Microscope (Fig. 8) Bee Or fe Ao a McLaren's Microscope, ne ‘Ring Foot (Fig. 9). fs 111 ‘chieck’s Revolver School and Drawing-room Microscope.— Winter’s and Harris’s Revolver Microscopes (Figs. 10 a and Band 11) . Jat Mea ieee: ly 112 Winkel’s large iDreenton Apion ane (Fig. 12) Wie a 5 115 Jung’s New Drawing Apparatus (Embr ae us fens powers (Figs. 13 and 14).. 3 9 116 Zeiss’s Micrometer Eye-picce (Fig. 15) .. Ne oer 7 118 Bulloch’s Objective Attachment (Figs. 16 and 1) a 118 Abbe’s Cameru Lucida (fig. 18).. .. .. . BE Wi aa 119 Millar’s Multiple Stage-plate (Fig. 19) a 120 Stewart’s Safety Stage-plate (Fig. 20) bid hee Nica 120 Parsons’ Current Slide (Figs. 21 and22) .. .. 1. 2. yy 121 Stokes’s Growing Cell (Fig. 23) .. ss. SUS Mee Oi oo 122 Nunn’s Pillar and other Slides .. .. ee 123 Beck's Condenser with two Diaphraym Plates (i. 2) 9% 124 Nelson’s Microscope Lamp (Fig. 25) . panne! : [OD 125 Developing Photo-micrographs 3 126 , Action of a Diamond in Ruling Lines upon 2 Giles 5 126 Test Diatoms in Phosphorus and Monobromide a ae URE 10 9 Beer shttieny 138 Microscopic Test- Objects (Fig. 26) Sh eulets Brae tie 139 Resolution of Amphipleura pellucida by Central Light. Pr 143 Bausch and Lomb Optical Co.’s “ Investiy ee Impr oved” ; Microscope Bn Pon a aoe: ‘5 144 Stage Condenser for Datanmee., “ 144 Bicentenary of Bacteria 144 Drawing from the Microscope < 145 CONTENTS, Microscopists at Dinner Photographing Microscopic Objects Simple Eye-piece Indicator .. Drawing from the Microscope Dr. Holmes and the Microscope .. Fakir and his little Fakes .. .. Astigmatic Eye-piece Aud Moreh Sita en rare Simple Revolving Table.. .. yah Seven le Microscope in Medical Gynecol Olan ers Fasoldt’s Micrometer. .. 1. «2 ae The President’s Address Ahrens’s Erecting Microscope (Fig. 28 ) Bulloch’s Improved “ Biological’? Microscope Cox’s Microscope mith Concentric Movements (Fig. 29) Geneva Company’s UB aroaeise (Figs. 30 and aoe “ Giant Electric Microscope” : : Tolles’s Student's Microscope (Fig. 32) ; Winter’s, Harris’s, or Rubergall’s Revolver iRaneseaine Geneva Co.’s Nose-piece Adapters (Fig. 33) Zentmayer’s Nose-piece (Fig. 34) Térnebohm’s Universal Stage Indicator Stokes’s Fish-trough (Figs. 35 and 36) Nelson-Mayall Lamp (Fig. 37) .. Standard Micrometer Scale Microscopic Test-Objects (Figs. 38 eel 39) Aperture and Resolution (Figs. 40 and i. The Future of the Microscope 50-00 7 100 Webt’s “‘ Optics without Mathematics” .. .. Bulloch’s Nose-piece . os Karop’s Table for Microscopical Poy, ean 20 Drawing with the Microscope .. .. Substitute for a eae Table .. “ Congress NOeseeaeD on “ Microscopists” and the poston ai the Micr aecaine so Revolving Table .. .. . eye on BC Penny’s Proposed uence 20 *o New Fluid of great specific gravity, tan ge atte of refines: tion, and of great dispersion .. 5 00 XXVU Part 1 On the Estimation of Aperture in the hercscope (Plate VI. T. ) Part 3 Note on the Proper Definition of the Amplifying Power v a Lens or Lens-system (Fig. 48) Hensoldt?s and Schmidt's simplified Reading Memoscorees Pe Geneva Co.'s Travelling Microscope (Figs. 51 and 52) Reichert?'s Microscope with modified Abbe Condenser (Figs. 58 and 54) .. .. . oe Reichert’s Polarization Weeeercoe (Fig. 55) Reinke’s Microscope for pee the Growth of leans (Fig. 56) 66) 00 Tetlow’s Toilet-bottle Micr ance (Fig. 57) Grifith’s Multiple Eye-piece (Fig. a Francotte’s Camera Lucida... .. PAGE 145 145 146 146 146 146 146 147 147 148 173 278 279 279 281 282 283 284 284 285 285 286 286 287 288 289 291 300 300 301 301 302 302 302 302 302 303 337 348 436 437 437 410 441 442 443 444 XXVill CONTENTS. PAGE Rogers’ New Eye-piece Micrometer .. .. « « «» Part3 445 Geneva Co.’s Nose-piece Adapters—Thury hope Selection of a Series of Objectives BEA Acie “ High-angled”” Objectives Zeiss’s A* (Variable) Objective and “* Optical Tube longi 4 (fig. 59) . 50 Bare Le os Queen’s Sani Mounting (Figs. 60- 62) . Boob h daly Loc Paraboloid as an Illuminator for Homayencons immersion Objectives .. Paraboloid for Ronating innate, m Lee, Fi igs. 63 and 64) erate 2s : . Horizontal Position of the ne oscope 06. 6c Flégel’s Dark Box (Fig. 65) Boh in Feussner’s Polarizing Prism (Figs. 66- 73) Abbe’s Analysing Eye-piece (Fig. 74) .. Measurement of the Curvature of Lenses New Microscopical Journals Bausch and Lomb Optical Co.’s Tiencwsde ss Investigator” Lantern Microscope i tieated: gee avers Selection of Microscopes .. .. .. as Homogeneous Immersion Cementing Brass on Glass Polarizer Physiology of ispecies Vision with the Mi icroscope ore. 80- —2) Dark-ground Illumination for showing Bacilli of Tubercle .. Admission of Ladies as Fellows On a New Form of Polarizing Prism (Figs. 87 ane $8 Microscope with Amplifiers (Fig. 89) Bausch’s Binocular Microscope (Figs. 90 and 91) Sohncke’s Microscope for Observing Newton's ae (Fig. 92) . Don 60 Harris and Son? s Portable Menoeccte Gas 93 an 94) . Seibert’s No. 8 Microscope (Fig. 95) . Reichert’s Large Dissecting aero and Hend Magnifier Ss (Figs. 96 and 97) 5 30 00 Geneva Co.’s Dissecting Micrgicdne (Fig. 98) Drailim and Oliver’s Microscope Knife al ey Ward’s Eye-shade (Fig. 100) es Endomersion Objectives Selection of a Series of Oigeuiees: : Correction eee for Homo RAS ~ immersion Ob- jectives Lighton’s Immersion Minirninaton (Fig. 101) P Iilumination by Daylight and Artificial bien Morente and Lieberkiihns Bausch’s New Condenser ( Figs. 102 and 103) . Glass Frog-plate (Fig. 104) ot Groves and Cash’s Frog-trough for ieoscanet nd Physiological Observations (Fig. aug Visibility of Ruled Lines : 99 99 ” 445 445 450 450 452 453 454 4595 455 456 462 462 463 463 464 464 465 4695 466 486 497 498-9 . Part 4 533 607 607 609 611 613 613 614 614 615 616 620 620 621 621 623 623 624 625 EE — CONTENTS. XX1X PAGE Mercer’s Photo-micrographic Camera (Fig.106) .. .. Part 4 625 Photographing Bacillus tuberculosis .. 1. 4. «1 46 ys 627 Beck’s * Complete” Lamp (Fig. 107).. -. « ess 628 James’ * Aids to Practical Physiology’ DA Ghievaitey asta teary 35 629 Postal Microscopical Society. .. «1 su oe swe Sigg 630 Resolution of Anyphipleura .. 2 65 sa 6s «2» oe gy 631 Home-made Revolving Table OMRON OG. Bron it AG 55 631 SCLEGLLON OfspDLtCTOSCOPCSIs me iNae eae anne st- ict nce us 632 Wenham’s Button 00 SoM pete Ue Ge ea” es 633 On Drawing Prisms (Figs. 120- -2) Part 5 697 Albertott’s Micrometer Microscope (Fig. 123). : % 793 Baumann’s Callipers with Movable Microscope and Fined Micrometer (Figs. 124 and 125) «. 1s use Sg 794 Geneva Co.’s Microscope Callipers oe se aoMieteiie! 5s 796 Griffith’s Club Microscope 04 do 09 797 Nachet’s Class Microscope (Fig. 127). 9 797 Nachet’s Microscope with Large Field a 797 Stephenson’s Aquarium Microscope (Fig. 128) .. a 798 Swift and Son’s Oxyhydrogen Microscope (Fig. 129).. on 799 Nelson’s Hydrostatic Fine Adjustment (Figs. 130- Bie ape ery, 800 Griffith's Nose-piece (Fig. 133) .. .. «. od tp 801 Kellner Eye-piece with additional Lens as a Boinctatecre 0 801 Osborne’s Diatomescope ASR EPO Rae ey » 802 Hardy’s Collecting Bottle .. .. .. «. oe 0 803 Eye-piece Amplification 59 804 Illumination and Focusing in Photo- Linear eye) 5) 804 Mitchell’s Focusing Glass for Photo-micrography 5 805 Photo-micrography in Legal Cases (Fig. 134) A 806 American Society of Microscopists 99 808° Health Exhibition .. % £08 Objective Changers 5 809 Riihe’s Microscopical aie a eS 810 Microscope Tube-length AG lod deo" ac 5 811 Plane Mirror for Microscope Sisiblen tielae oA Sanda stone o 811 On some Photographs of Broken Diatoms taken by Lamplight SNM: = Bcras OG .. Part 6 853 Japanese Microscope (Fig. 145) . F 99 953 Schieck’s Corneal Microscope (Fig. 146) i op 954 Zeiss’s No. X, Microscope (Fig. 147) .. .. «2 os on 954 Wray’s Microscope Screen (Fig. 148) dono & eee oop 956 Abbe’s Micro-spectroscope (Figs. 149-151) >... «. 4. 5, 957 Eingelmann’s Micro-spectral Objective (Fig.152) .. .. 4, 958 Mayall’s <* Stepped” Diagonal Rackwork Ce 153-4) . 93 958 Fasoldt’s Nose-piece (Fig. 155) . ; 60 ai ‘3 959 Spencer’s Dust-protector for Onertine oF 959 Suift and Son’s Goniometer Stage (Fig. 156) 3 960 Hartnack’s Goniometer Stage (Fig. 157) .. 3 960 Osborne's Diatomescope (Fig. 158) .. .. swe 39 961 Wallich’s Condenser (Fig. 159) .. e 963 Cells for Minute Organisms... .. oo «1 99 963 Stokes’s Spark Apparatus (Fig. 160) . 33 964 XXX CONTENTS. PAGE Bertrand’s Polarizing Prism... 8 ae earl 6 3965 Electric Illumination for neta: Mick oscopical, and Spectroscopical Work .. .. ie 966 Clayton and Attout-Tailfer’s ircoesomutie Plates for Gein micrography .. Acai AGL RSS Ch 969 Error in Photogr aptingh Blon-conpueeles ach Go

) 471 Hoyer’s Picro-Carmine, Carmine Slt, an Ger mine I ROUAP IO IAORED. 00, “a Mba Bn sBcl aR ne od) py 474 Dry, Ti ection Masses mn pae einer aigoe iss issn) bess aca. as 474 XXX1i CONTENTS. Imbedding Diatoms .. . aoe eel eae astm tate Zentmayer’s New Centering Turn- table (Fig. 75) .. « Phosphorus Mounts .. ode coche boraa-ote lb ati lieerio Styrax .. o» BOs | hGOk. ocala cia mocieeano Smith's New Mounting “Media Gi eee ticigliar Ome eeleinc WSS Cel (88g6 TD) oo uo on nS SS Closing Glycerine Cells. don irod | oa Getschmann’s Arranged Diatoms.. Classification of Slides .. O06 Od) 00) GO oor! Joe Blackham’s Object Bomes .. «1 «+ se se se a Stillson’s Object Cabinet Pillsbury’s (or Bradley’s) and Cole’ s Melng Cases gs TUT) 0000 50 How to send living none 50 Age oa fou Preserving Liquid for Anatomical Onjectsn Sei adyycon Blue Staining .. «. Si ihpr ial ecco hen dra Miedo eedoe ooo Crystals of Arsenic .. ., Sate let a eh How to Mount Casts .. «- Mounting Desmids ATOMS Gee vente tele Meters Staining Bacilli of Tubercle g0) Woo ‘oa 00 Measurement of Blood-corpuscles Naphthaline .. .. On a New Microtome (Figs. “93 ae 84) Methods of Investigating Animal Cells Born’s Method of Reconstructing ees om Mioascop ISECIIONS) se eel eel wie 20) 00 Shrinking back of T8296 of Oribatide in | Mounting Preparing the Liver of the Crustacea .. Preparing Alcyonaria.. .. Semper’s method of Making Dried Pra seneRTS Method of Detecting the Continuity a Pr ude: m Vegetable Structures Method of Preparing ae iors eins ‘ae the Microscope a0 c Se Md areas Chapman’s Microtome .. 0 Use of the Freezing Microtome .. io) hOnueOSh Odo Apparatus for Injection—Fearnley’s Constant Pressure Apparatus (Figs. 108-18) 0 Myrtillus for Staining Animal and Vedeiane Tissue Hartzell’s Method of Staining Bacillus Tuberculosis .. Safranin Staining for Pathological Specimens .. .. .. Collodion as a Fixative for Sections Hora p0 LEO FOTROPS KEES on oS Mounting in Balsam in Cells 0 Styrax, Liquidambar, Smith's and van Hepes Mean Groupiny Diatoms etn eee on dt : Quantitative Analysis of Minute oie) Dearmisns oo 0)./b9 Microscopical Evidence of the Antiquity of Articles of Stone Carbolic Acid and Cement for Algae .. .. «2 oe Catching Small Insects .. Boh fuinteehce Mounting the Skin of a Silkworm 658 CONTENTS. XXX1il PAGE Kidder’s Aeroscope se beliciewl) Moles Savi eee bela AMOR ses EArt 4s GOS Bubbles left in Fluid Mounts .. 2. sn ss wee Say 658 Clearing Fluid .. .. Hose Bot pc 659 Detection of Poisons and i carnination of Blood Stains .. Part 5 812 OURG JOfUSOTV co 0d 00 90 00 813 Perchloride of Iron .. os 813 Mounting of Hoan eatfon a= NO Slide for Onan Oyjecen » _ 813 Hematoxylin as a Reagent for Non- CS and Non- suberized Cellulose Membranes.. .. 00-00 814 Canarine for Staining .. i 815 Cultivation of Bacteria upon Oh ‘Slide (Figs. 135 anh 136) will) Staining of Schizomycetes in Sections and Dry Preparations ,, 817 Staining Fluid for Sections of Tubercle-Bacilli .; .. 2 818 Methods of Imbedding (Figs. 137 and 138) bor eodn WOOm lea 818 Hofimann’s Imbedding Apparatus (Fig. 1389) .. .. .. 45 821 Celloidin for Imbedding .. aaaleron Wheteh ee ele) Llsa 822 Reichert’s Microtomes (Figs. 140 and my sen ot, Mee 823 Decker’s Section-smoother (Fig. 142) .. .. «1 ws we gy 825 Griffith’s Turn-table (Fig. 148) .. “ ere came tate Matattnen oobi | ay 826 - Reversible Mounts ae WR bceinei noche MISE Me ccrye ooa52 826 Hinman’s Device for Mounting SOME ome Hane ino ashi eg lr 827 Preparing Schultze’s Solution .. 1. 1. 4» 00 we gy 827 Syanirate Chol JOKeMMClnNOUP 65 60 00 60. 60. 0d” ov . 827 Jerguaring Soqlkie CARGNE oo 05 60° 00 bo 00 06 gp 828 Gouining) iueroms Wide SIBGP 60 50 66. 60 60 0p) 829 Lyon's Mailing Case... .. 5 829 Action of Reagents in the Danian of Veceraie LIRR bn 6 SRR Tne i mae abe se 829 Reagents for Feros a in s Went Coils Bbioda OO, 106. ogy 832 Microscopical Examination of Chestnut-meal .. .. 0» 5 832 Microscopical Investigation of Dyed Cotton Fabrics .. .. 45 833 Microscopical Examination of Water for Organic Im- FOUOIS Gon ea) eae Ned 60. 09.00 , 833 Changing the Water in | Anuar ‘eiainng Wierosecerent Organisms 00 00. 00 a0 oo 00 835 Micro-Chemical Test for SedRiox 90 60° 00 eo 00 836 Micro-Chemical Reaction of Solanine.. 1. .. «. 4 836 Size of Atoms .. so Gh. Cm DO eobe Brey 836 Liquid Films and Molecular Mematinreen 00 60" oo) on! & 837 Air-bubbles in Glycerine Cell-mounting send avent a et * 837 Thoma Microtome Gc. 1a) Libth Teaco Son, oe Panel meen 838 Smith’s Mounting Medium .. 2. 0. 1» os as ogg 839 Peirce’s Slides .. . 60 |) Ol | OC; moony Boni loon Meany 839 How to Harden Balsam “Mounts elie resets PA xerskeaetciowy aera. weleiaackrs 840 Mounting Fresh-water Alge ‘is Spa eae Wea a eT OaaT lec 840 Hardy’s Collecting Bottle (Fig. 161) | 66 00. 00 on ler Bez Collecting, Desi dstpme mares tamce ene) n eas) aes ae 977 Preparing Embryos .. .. a) 00 80d) 00.) op 978 Method of Studying. the Amphibian ae Brea ers AGN cys 978 Preparing Planarians and their Eggs.. .. .» «. 0 4 978 ISOC IGHCOHED HOES bo a ab Bah ea J add) Ac 8S ep 979 Ser. 2.—Vo.. IV. Cc XXX1V CONTENTS. PAGE Imbedding in Sticks of Paraffin .. 1. «. « « « Part 6 981 “ Microtomy” .. Sox) Nea ae a Goel icde @ Scie bare raat 981 Gray’s Ether Treen Mier Mare soc oe ase cons oul: ty 981 Preparing Picrocarmine and Indigo Gere Bier ters aokcays Laois 982 Mercer's Solid Watch-glass (Fig. 162) .. «2 «2 « 4 983 Cheap Method of making Absolute Alcohol .. P » 984 Arranging Sections and Diatoms in Series... «1 .. «+ 4 984. Balsam of Tolu for Mounting .. . 5 985 Biniodide of Mercury and Iodide of Dephessioiy aa Phos phorus for Mounting APEC ORE da ar OO Loree ute hy bas ash 985 Chapman’s Slide-Centerer .. .. sve ameic a eel aeaiiee as 986 Indian Ink for examining Mier aneainte Orgone : 986 Apparatus for Aerating Aquaria 30 55 988 Detection of Sewage Contamination by the use i ‘the ier 0- sccpe, and on the Purifying Action of Minute Animals and Plants Ae niges aie scat ornate PEA ie eet 988 Examination of H andionitieg Be OMY rad s\oun 1 oO = wo gee han ae? Aes OO Stimondsia parudoxa —.. SERRE ae acre ere, ener tree Sncte hie GOEL) Monograph of the WWcleser dis ace. HS A as Flistology of Hehinodermata 08 sg) hee hee aos Lew eke erm eet 60 Nerious Syatemof HOlOwwurians co: 0. Se Sy as hiee ye ek we oe 62 Vascular Systeme of Eichinpgerms: ays ws Ne aw cease ae alee as 08 Nervous Sistem Of BOvpitd es ae 1s as eee ha ied Vee win, me OF Berman Meduse iy ii7 ag on) ea oer Selle Pom ha Meme Noreen, eek east Od Alleged new Type of Sponge SAL ee dere iN, Meeri ya Al Voraamaincr ss ccets 40K) Boology and, Anatomy Of, CHONG x6 2 he" Aa Sen taht Roe) pny Apel Cee unset OD New Silicious Sponges from the Gonte een Lee. ci marten Gal Rade 1as OO Parasitic Infusoria 2. .5 Se ONE sinieran My ne NP tia tenn Pantech g New Infusoria — .. Arai Ore eRe Sa Re ore gs Relationship of the Flagellata to ‘Alge “and “‘Infusoria Be GOR kg cea ae OS -- Transformation of Flagellata tnto Alga-like Organisms .. %. +» .. «. 69 WLELINS UN USTONSENVETE® ah eee Pogo ane AM oe eh ieee ian cient! leureee oe 70.. Cilio-Flageliata _ .. Se oe eo coals UN Oat omen a aaron Ce rey a ete ahs New Choeno-F Flagéllata ip Aigo ic eala VN og UD eA Bate SRI eD PS Irate a ee dE Anatomy of Sticholonche zanclea Syl Svea ota Reap mae MON te ely eae ood DOUUES OTE TNE HOTOMMUNEP CLO © 2355 es aly dei aah ha Jiael nh lees ea ee AE Developimentof. SUMO ynehugs sya aa ahi- ae Gems inal coat) ES | eee eee UE Borany. Relations of Protoplasm and Celi-wall in the navies CEU ea Wide ag ive oO Intercellular Connection of Protoplasts 2. 6. se ee ee ee we 6 Polyembryony of Trifuliwm pratense .. 6. ewe ee ts eee SG Mechanical Structure of Pollen-grains ©... 2.) ee ue ee a wee TE Rertitization of .Philodendron™ se 00 0 es ey ea se ee ww ee TT Fertiiization of the Prickly Pear Tas BCE Me ee ORR Ren I Cee Annual Development of Bust .. .. LO et oes Th Lenticels and the mode of their replacement 4 im “some ‘woody tissues ea ate eS Gum-cells of Cereals... .. REE aE oe Cee aaa, SOS 9). enor coy 78 Nucleus in Amylaceous Wood-eells SEO go Uae Saat aa gin i UN dimen) EO Peculiar Stomata in Coniferee .. 06 oe ae ee ee ee ee TD Root-hairs SER MO IO TE SNE LDA OS ea eS Sieve-tubes of Ciera cea a eh Cee as es er sd Spines ofthe Awana cee sees Vos oP wa wee eel owe ie Ve eal ee OL Tubers of Myrmecodia echinata .. ve SL Chlorophyll-grains, their Chemical, Morphological, aha Biological Nature . 81 Mechanism of the Splitting of Leguines ae 82 Acrial Vegetative Organs of Or chidee tH relation to their Habitat and "Climate .. 83 Assimilation of Carbonic ‘Acid. ky “Protoplasm which does not contain Chlorophyll... Pen eee ain eng eros OD Artificial Influences on Internal Causes of Growth . Deine ety tre areaAreaael eg ce SD Absorption of Feod by the Leaves of Drosera 2s 6. ue tsa te we 8B Mechanical Action of Light on Plants - : 84 Action of the Amount of Heat and of Maximum Temperature on the Opening of Flowers -.. Beat ea ay Shara eg eee eer OO Behaviour. of Vegetable ones Footie Gases Gerke ues ea een _ Influence of External Pressure on the Absorption of Water by “Roots 85 Contrivances for the Hrect. Habit of Plants, and Tee of iy ey: ‘ration -on the Absorption of Water... 4. ss os we A Beste <0 )) Sap a Wet Sse le oa ae a as Be RON aotas eee ae eR OO, Solid Pigments in the Cell-sap Bet alg Snipe de iets thpie lode ewe Cag ON Movement of Sap in Plants in the Tropics Ee A ete nes tate ceria Bry aay eee f Huudation from Flowers in Relation to Honey dein. a eee 87 Latex of the Kuphorbiacee .. ee el seimiceaet sts Crysialioids in Trophoplasts, and ‘Chromoplasts of Angiospern ms... 89 Formation and Resorption of Cystoliths .. a 90 Function.of Organic Acids in Plants _. eh cwee nec buses 100 Formation of Ferments in the Cells of Higher SORTA OLS sen SOOM Ge Poulsen’s Botanical Micro-Chemastry:. .. 0 ise se ee ve ae we we Classification: of: Opiioglossaced 26 sc eras. Sea Cae zee ee ee an 2 OF Rau rrors be C249) Summary or Current RESEARCHES, &c.—continued. PAGE Structure and Development of certain Spores .. +» 4 es ee ee as 9B Alkaloids and other Substances extracted, Jom “Fungi ela g oo eae ea Pe ee Developmemt of Ascomycetes 1s ve thie et aay ner oi sm ou tt eamiearaass Aen Conidia of Peronospora .. «+ «0 se ee ee oe te ete nD Pleospora herbarwm 1. s+ | ae be oe te ett ee ewe wD Chytridiacez On ee oe oo eo eo oe &e . 96 Phoma Gentian, a new Parasitic Fungus ES Me teas CS > 96 Chrysomyxa albida 2. +» ae ee eee tee Rees 96 Physoderma .. nore 1. 7* ee ee ee ¥ ws omen, - a ta aS - Bor S 3 : 7 5) Zz fs y Z Rie dna i , CEE OOS STE A DN MA A A OT A OL PA NT CN PAY LS EL NU DS eet at ae $a BR NG It ete SA Ses SST reece Irn COTS ROT Pree ARES ETS en Sey ITE ee ESTEE Kt 1. ELLCEELELELELEFEELLELEELEEGEBELEELELEEELEP EEE TET Eee ETE EL te RAR OAE MLN RG RAN HORARAB MARDER OREM AREREAMAALE RNNNNHNPNNNNM NHNNHYPNMNYNNYNHNHhd eepcoc wt ty opto to Coes CON NN bh bb OD Go. G9 ti) 2 OS GO OD 0D ins. “007892 “047262 086633 126003 165374 *204744 244115 *322855 *362226 *401596 -440967 -480337 -519708 *559078 7098449 ‘637819 *677189 *716560 *799930 *795301 *834671 *$74042 *913412 7952782 7992153 “070894 -110264 *149639 189005 *298375 *267746 *307116 346487 *B85857 “495228 °464598 “503968 *943339 * 582709 622080 *661450 -700820 “TA0I91 *779561 *818932 *858302 “897673 1 decim.) II. Conversion of British and Metric Measures. ; (.) Linrat. Micromillimetres, &c., nto Inches, &e. Be ins. mm, ins. | mm, 1. -000039 1 °039370 51 2 +000079 2 078741) 52 - “3 ‘000118 3 “118111 53 4. :000157 4. *157482 | 64 5s *000197 5 *196852 | &5 6 *000236 6 7236223 | 56 - @. +000276 a *275593.| 57. 8. -060315 8 *314963 | 58 S 000354 9 * 304354 59 10 -000394' 1¢@ (1em.) -893704| €9 (6 em.) 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Si -000827) 21 *826779 | 71 22 -000866| 22 ‘866150 | 72 83. -000S06; 23 °$05520 | 73 24 +000945) 2 *944890| ‘74 25 000984 | 25 “$84261 | "75 £6. .-001024 | 26 1:°023631 |. 7S 27 -:001063 87 1-063002 | ‘7'7 28 001102 28 1:102372 | ‘78 é 001142 | 39 1°141743 | 79 $0 -001181 | 80 (8cm,) 1-181113 | &0 (8 em.) 31 -001220| 381 1°220483 | §2 82 -001260' 82 1°259854 | $2 $3 -001299| 83 — 1:299224 |. 68 84 +001239) 2 1:328505 e4 25 +:001378 | 85 1°377965.|. 8&5 So. <°001417| 36 1:417336 |. 86 37 601457 | 37 1°456706 | 87 38 -001496) & 1:496076 | &8 29 *001535 S - , 1:535447 | &9 40 -001575 | 40 (4em.)1°574817 | €O (9 em.) 41 -001614 | 41 1°614188 Oiezs 42 +601654 | 42 1-653558 | &3 43 .-001693 48 1°692929 SS 44 -(001782 | 44 1:7382299 | G4 45 :001772; 45 1-771669 |. S5 46 01811 | 46 1:811040| 96 47 -001850 | 47 1:§50410 | 97 48 -001850| 48 1°889781 | .S8 49 -001929 | 49 1 17929151; $9 5O +001969 | 50.(5 em.) 1-968522 | 160 C0 em.= 60 -002362 : 7S 002756 decim. ins. 80 -003150 1 3937043 90 -003543 5 7° 874086 160 -003937 3 11-811130 200 007874 4. 15°748173 800 -0118i1 5 19685216 460 :015748 6 93 - 62295 500 -019685 7 97559302 600 -023622 8 31°496346 700 -027559 9 35° 433389 8900 -031496 10 (1 metre) 89°370432 S00 -035433 = 3280869 ft. || 1060 (=1mm:) 1-G695623 yds. ~283485- *031523" Inches, §c., into Micromillimetres, Ge. ins. B ' ssoo0.. 1015991 soiss 17269989 tseo0. «1° 693318 sotaa 62°539977 sda 2°822197 soso. 3°174972 woes 37628529 sone £°283295 sds5 3D 079954 sdsg 67349943 sess. 8°466591 song 127699886 soso 25°399772 mm. aire *028222 —— 7031750 ab5 “036285 aig 1042333 st, *050800 aie 056444 siz 068489 so OT2571 =o 1084666 sig. * 101599 wie ~~ 126999 ai, | 1169332 S ——— == SS ee SS = tail-piece. Not only do the mirror and the substage swing on separate tail-pieces, either above or below the stage, but they can also ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 111 be rotated completely round the stage, so that the direction of the illumination in azimuth can be more readily varied than is the case with Zentmayer’s form of tail-piece. The stage consists of a fixed ring attached to the limb by an angle-plate of brass; this ring carries above it the rotating object- stage, and beneath a rotating collar is fitted, which has a shoulder attachment at right angles carrying the two tail-pieces on an axis slightly above the plane of the object-stage, and allowing of their rotation round the optic axis. The angle-plate, by which the stage- ring is fixed to the limb, is so arranged that the shoulder carrying the tail-pieces will pass behind it, and there is therefore no obstruction to complete rotation. This plan of suspending the tail-pieces is far more convenient than that devised by L. Jaubert,* or that of J. Mackenzie.} McLaren’s Microscope with Rotating Foot.—Mr. A. McLaren has devised a simple plan of giving greater stability to Microscopes Nie, mounted on a pillar support on a horse-shoe foot, which are very liable to be overturned when much inclined from the perpendicular. The plan consists in making the foot rotate at its junction (fig. 9, A) * See this Journal, i. (1881) pp. 514-5. + Ibid., pp. 825-7. 112 SUMMARY OF CURRENT RESEARCHES RELATING TO with the pillar support, so that when the Microscope is required to be used much inclined the horse-shoe base can be turned round as shown in the fig. This increases the stability of the Microscope, and adds so little to the original cost that the makers of these inexpensive forms may profitably adopt the suggestion. Mr. McLaren also uses a system of fine adjustment applied at the nose-piece (shown in the fig.), consisting of a ring fitting in the lower end of the body-tube, in which the nose-piece proper, carrying the objective, is screwed by means of a very fine screw, 200 threads to the inch. The focusing is effected by turning the nose-piece either way, by which the objective is raised or depressed very slowly owing to the fine pitch of the screw. By this system, which is also applied to some old forms in our possession, the objective is made to rotate with every movement of focusing, which cannot be commended. Schieck’s Revolver School and Drawing-room Microscope. — Winter’s and Harris’s Revolver Microscopes.—F. W. Schieck has just issued the Microscope shown in fig. 10 a and 8, intended for school and drawing-room demonstration. The peculiarities of the instrument are fully set forth by Herr Schieck himself in the fol- lowing statement (translated), which also includes some very original directions for preparing objects :— “The management of a Microscope of the ordinary construction, with fixed stage, movable tube, different eye-pieces, objectives, &c., offers, in most cases, so many kinds of difficulties to the lay public, especially to young students, in the inspection of the preparations accompanying the Microscope, and in the adjustment of the image, but especially in the self-preparation of objects, that this important and interesting instrument has not yet attained that position either among our intelligent youth, or in our drawing-rooms, as an object of instructive entertainment, which befits its high ethical importance. The management of the Microscope has even been found so intricate, that in consequence (as I have had the opportunity of seeing on numberless occasions) it has been very soon put aside again, after a short trial. My new Microscope entirely removes this disadvantage. It is of such simple construction, and its management so thoroughly easy, that any one, even without any previous acquaintance with the use of a Microscope, is able to observe with it, as well as to make for himself beautiful microscopical preparations. The new Revolver Microscope has, instead of a stage, a vertical drum, turning on its axis (like the chambers of a revolver), in which twenty different very beautiful and instructive preparations, from the three natural kingdoms, are arranged, which, on turning the drum, are brought successively into the field of view of the Microscope. The movable mirror is in the centre of the drum, and is easily and conveniently adjusted. The Microscope is provided with a hinge for inclining the stand, so as to be able to observe conveniently whilst sitting. The twenty preparations are numbered, and an explanation of them accompanies each Microscope. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 113 As the Microscope has only one objective, and one eye-piece, and therefore only admits of a fixed magnifying power, a special focusing arrangement is not necessary. The tube of the Microscope is so fixed, that the image of the preparation is always in the field of view of the eye-piece, and only in the case of differences in the eyes of observers is a small shifting of the tube, amounting to a few millimetres, requisite. For this purpose the body-tube is easily pushed with the hand up or down, guided by a pin working in the Fig. 10 a. Fic. 10 B. small slit in its sheath, without ever thereby losing sight of the image of the preparation, as happens with other Microscopes. The magnifying power is such that most popular objects can be seen distinctly and perfectly. The images are of unsurpassed sharp- ness and clearness. The field of view is very large, and all preparations which are not more than 4 mm. in diameter can be seen entire at one view. An entirely special advantage of this new Microscope is the uncommonly simple manner in which the teacher or student is enabled Ser. 2.—Vort. IV. I 114 SUMMARY OF CURRENT RESEARCHES RELATING TO by its means to prepare by himself a new series of twenty preparations at pleasure. The hitherto general practice of laying the object to be inspected on large glass slides, and fastening over them the thin, round or square, cover-glasses, presented so many difficulties that a preparation seldom succeeded well, especially if it were put up for any length of time. With each of my new revolver Microscopes is given a second stage- drum, with twenty empty apertures, and a sufficient number of small round glasses and spring-rings for firmly fixing the preparations. The stage-drum with the preparations already attached to the Micro- scope is unscrewed from the milled disk, and the second empty drum put in its place. The insertion of a new object is so exceedingly simple, that direc- tions for it seem, properly speaking, superfluous. In the first place a small round glass is washed clean, and with the forceps belonging to the Microscope, is laid in one of the apertures, then the object to be examined is laid in the middle of this glass, either dry or with mounting liquid (glycerine, gelatine, Canada balsam, or in cases where only a rapid observation of an object is required, even water, spirit, &c.), and covered with a second previously cleaned glass, fastened down with a spring-ring which goes into a small groove made for it, and the preparation is ready. (!) It must, however, be here observed that all hard objects (especially insects) must, in order to succeed well, be previously heated for a few seconds in a small reagent glass, with caustic potash over a spirit flame, by which means the preparations become soft and quite transparent. The preparations are perfectly protected from dust by a pasteboard cover, and care must be taken always to replace the cover over the stage-drum, after using the Microscope. If, in spite of this, dust should after a time fall upon the preparations, it must be carefully brushed away from both sides by the soft hair brush accompanying each Microscope; any other cleaning of the preparations is never necessary. If desired these Microscopes can be supplied with special objects previously given me to prepare, and for the requirements of schools the stage-drum can be fitted with botanical, zoological, or minera- logical preparations. Price according to agreement. This entirely new, and in every respect original and practical Microscope offers to every one such a fund of entertaining and in- structive matter, and will prove to the teacher as well as the student such an inexhaustible source of suggestive occupation, by which to pass the leisure hours usefully and pleasantly, that there is scarcely anything better fitted for a present, always gladly seen, especially by the ripening student. The price is fixed as low as possible, and con- sidering the prices ruling here may be called very cheap.” Herr Schieck intended, we have no doubt, to be strictly accurate when he announced his instrument as “entirely new” (ganz neu) and “in every respect original.” But it was in fact anticipated by two now in Mr. Crisp’s collection, which were made more than fifty years ago, by 'T'’. Winter (simple) and Harris and Son (compound, fig. 11). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 115 They are in principle identical with that of Schieck. The revolving object-holder is, however, made of ivory, and is much larger, being 43 in. in diameter and 13 in. wide. There is also a double row of apertures for the objects—one row for transparent, and the other for Fic, 11. opaque—so that, instead of 20, it holds 44 objects. There is also at one point of the circumference an intermediate set of apertures, ap- parently for inserting further objects on disks, corks, &c. (In Winter's there is a complete row of 19 of these apertures, 10 with corks). Winkel’s Large Drawing Apparatus.* — This (fig. 12) is in- tended for drawing objects under a low power, and also without any magnification. On the side of the standard A, and above the stage T and mirror §, is a cross-arm B carrying a lens L, and over it a small right-angled prism P, which acts as a camera.t On the other side there is a longer arm, also with a prism for drawing objects in * Dippel’s ‘Das Mikroskop,’ 1882, pp. 632-3 (1 fig.). + The text states P to be a prism (protected by a ring) though the fig. hardly agrees. 12 116 SUMMARY OF OURRENT RESEARCHES RELATING TO natural size. The arms can be raised and lowered by the sliding within A of the support to which they are attached, the screw on the right clamping it. P | Fie. 12. @ L i TTT E = SSS = i ill = Jung’s New Drawing Apparatus (Embryograph) for Low Powers.*—H. Jung was induced, by the inconvenient or ineffective performance of other drawing apparatus, to construct a new one (fig. 13) in accordance with the friendly advice of Professor v. Koch, giving powers of about 1 to 20 or 4 to 30 in continuous succession. Upon the heavy square iron foot rests (besides the column and the bar P, movable by rack and pinion) a concave mirror to illuminate transparent objects. The latter is 80 mm. in diameter, and consists of a plano-convex lens silvered at the back. It is supported on a hinge-joint, which is attached to a short rod fitting into a spring- tube h, and this is screwed to a carrier T having a longitudinal slot. The carrier rests on the foot to insure greater stability, and on loosening the screw S which clamps it, it can be moved so as to obtain any desired position of the mirror, either by turning it round the screw as a pivot, or by sliding it along the slot. Upon the column is a stage 75 mm. deep, and 108 mm. wide. The stage, instead of a round aperture in the centre has a horseshoe * Zeitschr. f. Instrumentenk., iii. (1883) pp. 165-7 (2 figs.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. Jy aperture 40 mm. wide, which can be wholly or partially covered by two sliding plates. A special Briicke magnifier (with variable power) screws on the arm M. The arm has also a spring-tube into which a smaller mirror VidmadaTi TORREREEREO cm CO ut Wiilin, _ ore can beinserted. ‘This is for illuminating opaque objects, and receives its light from the larger mirror below. The focus of both mirrors is so regulated that with high powers the theoretically possible maxi- mum of illumination can always be nearly attained. For very weak illumination there is on one side a plate of opal glass. “The mirror has the great advantage over ordinary illuminating lenses that the field of view is always somewhat faintly and evenly illu- minated, which extraordinarily facilitates the visibility of many natural objects which have not sharp outlines.” The upper mirror can be placed in any position with regard to the axis of the lower, and can besides, for special objects, be put in the spring-tube of the lower mirror. 118 SUMMARY OF CURRENT RESEARCHES RELATING TO The Briicke lens consists of two achromatic objective lenses and a concaye eye-lens. The objective lenses can be moved apart or brought nearer to one another by turning the ring R. In the same way the eye-lens can be placed at various distances from the objective by pushing the tube N up or down. This tube is so sprung in the inner fastening that by a somewhat firm pressing together of the two knobs k, the friction of the two tubes is lessened and an easy and smooth movement is obtained. For very low powers the lower objective lens can be removed. By this combination and also two stronger eye-pieces all gradations of power, in the given limits, can be obtained. The extent of the field of view is in inverse ratio to the power within the limits of 65 to 7 mm. For convenient drawing a camera lucida is attached, which like Zeiss’s allows the drawing surface to be inclined about 22° to the table. On turning the ring R, or on moving the Fic. 15. tube to alter the power the camera always remains in the same position with regard to the ocular and the drawing surface, which is claimed to be “an advantage not to be undervalued, and not considered in many instruments.” In order to use the instrument for dissecting there are hand-rests, made to be easily removed. They consist of two hollow boxes (fig. 14) about 2/3 the height of the stage. They are attached by the button-headed screws ¢ to the foot of the instru- ment, being inserted in the holes ¢, and c, (fig. 13) and the hinged tops can be set at different inclinations by the support and rack. Zeiss’s Micrometer Eye-piece.—This (fig. 15) is noticeable for the manner in which the micro- meter disk is inserted. The eye-piece divides a little below the middle of its length, and has an additional piece between the upper and lower portions to which they are screwed. In this the micrometer disk is placed. The eye-lens is also in a sliding tube for adjustment to different sights. Bulloch’s Objective Attachment.—Mr. W. H. Bulloch has de- vised the objective-attachment shown in figs. 16 and 17. A is the nose-piece adapter to screw on the Microscope, and B is the ring, provided with three wedge-shaped studs, to be screwed on the objective. Three slots are cut in the body of the lower cylinder of the nose-piece A, and three similar slots in the inward projecting rim of a rotating collar. When the two sets of slots correspond, the ring B, with the objective attached, can be slid into the nose-piece, and then the studs are locked firmly by a slight turn of the rotating collar, which causes its projecting rim to slide over the outer halves of the studs. By reason of the wedge form given to the studs, the collar can be made to press down upon them with more or less force. ‘The objective cannot be removed from the nose-piece until the rotating collar is turned back to the normal posi- tion, releasing the studs. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 119 With this device both hands must be used either in attaching or removing the objective, and no provision is made to insure accuracy of centering. In the apparatus from which the above description was Fic. 16. Fic. 17. made the objective had a lateral play at the shoulder of about 1/50 in. when the collar was se- B cured with moderate force. Such loose fitting would be found very inconvenient in the registration : of the positions of small objects with high powers. Altogether, we cannot but think that the appa- ratus is more complicated than is at all necessary. Whilst it has the studs of Nelson’s form it lacks the simplicity of the turn of the objective with the same hand that holds it, and whilst it has the rotating collar of the Watson-Matthews form (amply sufficient to hold the objective) it has the additional complication of studs in place of a simple conical fitting. Abbe’s Camera Lucida.*—G. Kohl gives the annexed fig., 18, of Fie. 18. 1 I 1 I ‘ 1 1 1 1 Lug in Hh ail Ey ; ae i i Mf dat . aw Hy. oa ce A YY what he terms “ Boecker’s new drawing apparatus after Dippel,” but which is in reality Professor Abbe’s Camera Lucida.f * Bot. Centralbl., xvi. (1883) pp. 385-6 (1 fig.). + See this Journal, iii. (1883) p. 278. 120 SUMMARY OF CURRENT RESEARCHES RELATING TO The novelty consists in the introduction of the tinted glass plates * rrr inthe path of the rays from the mirror. Also the upper part of the apparatus (mirror p, its arm a, the glasses rr r, and the plate o 8) is movable on the pivot g upon the lower plate, which forms part of the tube h fixed to the eye-piece by k. Millar’s Multiple Stage-plate—The object of this stage-plate (fig. 19) is to facilitate the exhibition of a series of slides so that they may be observed successively without having to remove and replace each object separately. The base-plate slides on the stage after the upper stage-plate is taken off, and it holds six slides. Each of these is fixed by two small i SSS Ty ~s SS ny = == su UsHL Pause a erCeTTAUATN TAUNTS cre PLUTON TTT y RATTUAMEODCEEOSUE AT HH UMMA DULL MCCUE UL UHILILLL screws (passing through the two longitudinal bars) which press the slide against springs attached to the base-plate, there being six springs beneath each bar. The base-plate can be readily pushed in either direction by the hand when it is desired to examine a different object. The mechanical movements of the stage will bring various parts of an object into the field, but it is easy to adjust each slide on the plate in the first instance so that the object shall be central with the optic axis, there being sufficient spare room to move the slide both laterally and vertically. Stewart’s Safety Stage-plate——This very simple device (fig. 20) was designed by Mr. C. Stewart to provide an economical but Fic. 20. effective arrangement for protecting slides from breakage when being exhibited under high powers to large classes of students. It consists of a wooden slip the length of an ordinary slide and * See this Journal, iii. (1883) p. 119. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 121 rather wider, with a central aperture and two side pieces (4 in. high), capped with thin strips of brass projecting at either end of the up- rights as shown in the fig. Across the projecting ends two small indiarubber rings are stretched and the slide is passed through these rings and thus suspended. If now the objective is brought down on the slide the latter sinks on the least pressure and ample warning is given to the observer. Parsons’ Current-Slide.—Mr.’ P. B. Parsons has devised the new form of current-slide shown in figs. 21 (section) and 22 (perspective), which he describes as follows :— “The slide consists of two plates, pierced with central apertures Fig. 21. i surrounded by tubular projections, and fitting together like a live-box. The top one is raised or lowered by a milled head fixed to the lower one and working in a thread cut on the tube of the upper. Two pins prevent the plates from coming apart or turning on each other. The top plate has a hole at one end for the water supply and a Fig. 22. Sm —— === — == iS similar hole on the other for the waste, a piece of movable brass tube fitting into each. The supply tube has a valve for regulating the quantity of water admitted, and beyond this is an indiarubber pipe connected with the water-vessel. A double-necked bottle is very convenient, so that a fresh supply of any fluid can be introduced without disturbing any- thing. The advantages of this arrangement are :— 1. The depth of the cell is easily adjusted while on the stage, and the object can be brought within reach of fairly high powers by simply reducing the depth of water to a thin film. When not under examination with such powers the cell can be deepened, giving plenty of space with a constant current of fresh water, and yet enabling the observer to keep the object in view with a lower power. 2. The diameter of the cell, while large enough for all ordinary 122 SUMMARY OF CURRENT RESEARCHES RELATING TO purposes, admits of the use of very thin cover-glasses, -005 or «004 in., and when the cell is screwed up an 1/8 in., 1/10 in., or even 1/12 in. might be used if required. 3. The water supply is perfectly under control, and as there is at the same time no filtering action, the object can be supplied with water containing anything necessary to the life of the object. 4, The current is not interfered with by reducing the depth of the cell. 5. Objects can be easily put in, taken out, or manipulated in any way by stopping the supply and sliding the glass cover (which by preference should be square) downwards till the opening is large enough to do what is required. 'To replace the cover, slide it up till there is the least possible opening left and then fill up any air-space in the cell with water from a fine syringe before pushing it quite over the edge. If the under side of the cover-glass be slightly greased at the corners there will be no risk of it floating off. This slide is manufactured by Messrs. Swift and Son, and can be made of varying depth and diameter to suit special purposes.” Stokes’s Growing-cell.*—Dr. A. C. Stokes cements to a slide a disk and two rings made from cover-glass,{ the rings having a small piece broken away from each and arranged as shown in fig. To use, place on the central disk a small drop of the water con- Fic. 23. taining the organisms to be kept alive, and over it arrange a large square cover, taking pains to prevent the water from overflowing into the inner annular space. With a camel’s hair pencil carefully, and in small quantities, add fresh water at the top or side of the square, until the space covered by the latter and bounded by the outer ring is filled. It will be found that this water will flow between the square and the upper surface of the exterior ring, will enter through the break in the latter, partially filling the outer annular space, and by capillary attraction will occupy a part of the vacancy between the cover and the interior ring, as shown by the diagonal lines in fig. 23, but unless too much water is used, or is supplied in too great quantities at a time, it will not pass the opening in the inner ring, thus leaving * Sci.-Gossip, 1884, pp. 8-9 (1 fig.). + These can be punched out by the method described by Dr. Beale, «How to Work with the Microscope,’ 5th ed., 1880, p. 73. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 123 an abundance of air to supply the animal life under observation. The imprisoned air at once becomes saturated with moisture, as evidenced by the fogginess of the cover; the central drop cannot evaporate, and the external water will not come in contact with it if care is taken in filling and in adding that lost by evaporation. When not in use, the slide is placed across a small vessel of water, a double and twisted thread arranged in contact with the edge of the square cover, and the whole left for another examination at some future time. Nunn’s Pillar and other Slides. *— Dr. R. J. Nunn, under the heading of “ The Pillar-Slide—a new slide for the Microscope,” writes, “ Hivery microscopist knows the difficulty of estimating exactly the amount of fluid which will completely fill the space between a cover and the slide, and consequently a bibulant must be applied to absorb the excess almost always present. This takes a little time, which, to one who has many examinations to make, and who is otherwise pressed, is a matter of some importance. The following is a description of a slide intended to obviate this difficulty :— Take a small thick cover (round or square, as desired) and cement it on the centre of a slide with Canada balsam. Let this harden thoroughly so that the cover will not slip during warm weather, and also to prevent water insinuating itself between the glasses during the frequent washing to which it will be subjected. Of course it would be better to have these little pillars ground upon the slides, but with care in using them the cemented ones will answer every purpose. A drop of the fluid to be examined is placed upon the pillar just described, a cover larger than the pillar is placed upon it, when it will be seen that the excess of fluid flows into the annular space sur- rounding the pillar. Not the least advantage of this new form of slide is that evaporation takes place from the fluid in this annular space, and may go on for a long time without affecting the stratum under examination. Tf desired, the annular space may be filled with oil, and evapora- tion thus be entirely prevented.” Under the heading of “ Chemical—new slide for the Microscope,” is the following :—“ For the application of chemical tests to fluids under microscopical examination, the ‘pillar slide’ presents many advan- tages. ‘The method usual in such cases is to place a drop of the reagent at one edge of the cover and a bit of blotting-paper at the opposite edge, with or without a hair inserted between the cover and the slide to facilitate the inflow of the reagent. If the circular pillar-slide be used, then the cover must be pushed so that all the space is on one side; there will thus be formed a crescentic instead of an annular space. It is evident that in the latter, if the space is filled with reagent it will affect the film, but slowly, because evaporation takes place from the reagent itself, and there is nothing to draw it between the cover and the pillar. In the round * Sep. repr. from Trans. Med. Assoc. Georgia, 1883, pp. 21-4. 124 SUMMARY OF CURRENT RESEARCHES RELATING TO pillar this is best corrected by having the diameter of the cover smaller than that of the pillar, and pushing it to one side so as to project a little beyond the pillar, the lunate space thus formed is filled with reagent, while the rest of the edge of cover is evaporating and drawing upon the reagent to supply the deficiency thus created, or, to hasten the reaction, a bit of blotting-paper may be applied in the usual way. Another good way is to use a square cover: let one of the corners project beyond the pillar, and under this corner put the drop of reagent, in this way nearly the whole of the edge of the cover will be left free for evaporation, and the rapidity of the reaction will of course be proportionately great. If desired, a different reagent may be placed under each of the four projecting corners of the square cover. The ‘square pillar-slide’ seems, however, best adapted to this class of work, with a cover the same size or smaller than the pillar, and projecting a little beyond it; the reagent will then occupy one side of the square and evaporation go on from the other three sides. If an oblong cover is used which projects on opposite sides of the pillar, then the same or different reagents may be placed on opposite sides of the same specimen, without danger of mixing with each other.” Under “ Slides with hollows for chemical reactions” Dr. Nunn says ‘‘Many of the advantages of the pillar slides for the observa- tion of chemical reactions may be obtained by using polished glass slides with one or more hollows. In using these the drop of fluid to be examined is placed by the side of the hollow, or between them, if there be two or more, and the cover is allowed to project over the hollow or hollows a little distance; under this projecting edge the drop of reagent is placed, and the bit of blotting-paper may be used as usual upon the slide if desired.” Beck’s Condenser with two Diaphragm-plates.—Fig. 24 shows the condenser which accompanies Messrs. Beck’s Pathological Micro- scope (Vol. III. 1883, p. 894). The peculiarity of its construction is that it has two rotating diaphragm-plates, one with the usual series of (7) aper- tures of different sizes, and the other with one clear aperture and three others filled with blue glass of vary- ing tints, for moderating the light. The former is placed at a distance below the lenses sufficient for accu- rate centering of the condenser. As shown in fig. 24, the con- denser is for use with the smaller stands, but by reversing the optical combination and screwing it on the opposite side it is available for large stands. By the removal of the sliding cap which carries the highest power lens of the three of which the optical combination is composed, the condenser is suitable for use with low-power objectives. Fic. 24. 11 c¢ ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 125 Nelson’s Microscope Lamp.—Mr. H. M. Nelson some time ago devised the lamp shown in fig. 25; but no description or figure of it has been issued till now. The principal points in the design are (1) that the flame (using either the edge or the broadside) can be brought much nearer to the surface of the table than usual, which is secured by making the oil-well very shallow, large enough however to hold ART &.SON-| ia Looe (I sufficient for eight or nine hours’ work, and with means for replenish- ing the supply of oil without touching the flame; (2) the metal chimney is arranged to cut off all the light except that required for actual use with the Microscope, and the only glass required is an ordinary 3 x 1 slip which slides in a groove about an inch in front of the flame and can be readily removed for cleaning ; (3) the conden- sing lens is of the compound Herschellian form, by which a clearer disk of light can be obtained than with the usual bull’s- -eye, and is provided with means of adjustment in all directions. The lamp was constructed by Messrs. Swift and Son. 126 SUMMARY OF CURRENT RESEARCHES RELATING TO Developing Photo-micrographs,*—The microscopist who occa- sionally photographs his specimens finds that his developing solu- tions deteriorate by keeping, and often when he comes to use them, after standing untouched for some time, they do not act properly. Especially is this true of developers containing pyrogallic acid, which, as ordinarily made, soon lose their strength. It is customary to make up the solutions and keep them ready for use, but owing to the cir- cumstances above mentioned, this plan is not a good one for micro- scopists who only use them occasionally. Mr. R. Hitchcock has adopted the following plan for developing, which enables fresh solutions to be readily made without loss of time. There should be always at hand citric acid and pyrogallic acid in powder, strong ammonia (*880), and a solution of potassium bromide, 50 grains to the ounce of water. When about to develop the plates, dissolve 1:5 grains of citric acid in 8 ounces of water. In practice it is not necessary to weigh out the exact quantity, as it can be measured on the point of a knife, after a little experience. Then take half a drachm of ammonia and mix it with 8 ounces of water. Go into the dark room with the solutions, put the exposed plate into the developing dish, and proceed as follows: for a 4 x 5 plate take 1 ounce of citric acid solution and add to it 2 grains of the pyro- gallic acid in powder, measuring that quantity in the hand, or on a spatula. It dissolves almost instantly. Then add one ounce of the ammonia solution and a drop or two of the bromide, and flow the whole over the plate. The development proceeds slowly, and may be controlled in the usual manner by adding more bromide, or a few drops of dilute ammonia, as the case may require. Action of a Diamond in Ruling Lines upon Glass.j—Prof. W. A. Rogers writes, ‘In offering a communication upon the subject in- dicated by the title of this paper, I am not unmindful of the fact that I enter a field in which I acknowledge a master. Since the death of the incomparable Nobert, Mr. Fasoldt, of Albany, stands easily first in the art of fine ruling. I desire to repeat here the reply which for the past three years I have invariably made to inquiries for test-plates from my own machine—viz. that with Mr. Fasoldt’s special facilities for this class of work he can, I have no doubt, produce far better results than it would be possible for me to obtain by chance efforts. T have thought it better to confine my attention to another equally important problem—viz. an attempt to obtain copies of the im- perial yard and of the metre des archives, at the temperature at which they are standard, to subdivide these units into aliquot parts and then to obtain a microscopical unit whose subdivisions should be so nearly equal that the Microscope would fail to reveal the difference. The first part of this work has been mainly completed. Two independently obtained copies of the imperial yard yield nearly identical values for the length of this standard unit. Three indepen- dent comparisons with the métre des archives agree within very narrow limits in defining the absolute length of the metric unit, both * Amer. Mon. Micr. Journ., iv. (1883) p. 198. + Proc. Amer. Soc. Micr., 6th Ann. Meeting, 1883, pp. 149-65. ZOOLOGY AND BOTANY, MIOROSCOPY, ETC. 127 of 82 and 62 degrees Fahrenheit. The subdivision of these units into aliquot parts—the yard into inches and the metre into centimetres— has been so far completed that any errors which may remain will not affect the microscopical unit sought. With regard to the exact sub- division of these units, I can only report progress. Notwithstanding this abandonment of attempts to produce test- bands of the Nobert pattern, I have recently taken up the subject again, somewhat with the view of testing the claim of Mr. Fasoldt that he has succeeded in ruling lines one million to the inch, and especially by the claim that the existence of a spectrum in the bands is an evidence of the reality of the separate lines. The latter claim does not appear to be well founded. Aside from being at variance with theory, it can easily be disproved experimentally. Before proceeding further with this investigation, I beg to refer to a theory proposed by the writer in a paper presented to the American Academy of Arts and Sciences, in relation to the method which Nobert may possibly have employed in the production of his test-plates. Briefly stated, this theory is that the lines composing Nobert’s bands are produced by a single crystal of the ruling diamond, whose ruling qualities improve with use. In the light of subsequent experi- ence this theory may be stated in the following way: Whena diamond is ground to a knife-edge, this edge is still made up of separate crystals, though we may not be able to see them, and a perfect line is obtained only when the ruling is done by a single crystal. When a good knife-edge has been obtained the preparation for ruling consists in finding a good crystal. Occasionally excellent ruling crystals are obtained by splitting a diamond in the direction of one or more of the twenty-four cleavage planes which are found in a perfectly formed erystal. A ruling point formed in this way is, however, very easily broken, and soon wears out. Experience has shown that the best results are obtained by choosing a crystal having one glazed surface and splitting off the opposite face. By grinding this split face, a knife-edge is formed against the natural face of the diamond, which will remain in good condition for a long time. When a ruling erystal has been found which will produce moderately heavy lines of the finest quality, it is at first generally too sharp for ruling lines finer than 20,000 or 80,000 to the inch, even with the lightest possible pressure of the surface of the glass. But gradually the edges of this cut- ting crystal wear away by use until at last this particular crystal takes the form of a true knife-edge, which is parallel with the line of motion of the ruling slide. In other words, when a diamond has been so adjusted as to yield lines of the best character its ruling qualities im- prove with use. If Nobert had any so-called ‘secret,’ I believe this to have been its substance. The problem of fine ruling consists of two parts—first, in tracing lines of varying degrees of fineness ; and, second, in making the inter- linear spaces equal, The latter part of the problem is purely mechanical, and presents no difficulties which cannot be overcome by mechanical skill. It will be the aim of the present paper to describe the more 128 SUMMARY OF OURRENT RESEARCHES RELATING TO marked characteristics of lines of good quality ruled upon glass, and to illustrate these characteristics by corresponding specimens. To one who is familiar with Nobert’s bands a perfect line need not be described. It is densely black, with at least one edge sharply defined. Both edges are perfectly smooth. Add to these characteristics a rich black gloss, and you have a picture of the coarser lines of a perfect Nobert plate. How are those lines produced? In the study of the action of a diamond in producing a breaking fracture in glass the Microscope seems to be of little service, but we can call it to our aid in the study of its action in ruling smooth lines. One would naturally suppose that a line of the best quality would be produced by the stoppage of the light under which it is viewed by the opaque groove which is cut by the ruling diamond. Without doubt this is the way in which lines are generally formed. But it is not the only way in which they can be produced. An examination under the Microscope will reveal the fact that in some instances at least, a portion of the glass is actually removed from the groove cut by the diamond; and that the minute particles of glass thus removed are sometimes laid up in a windrow beside the real line, as a plough turns up a furrow of soil. On the finest plate I have ever produced every line remained in perfect form for about two months. I then first noticed a tendency on the part of some of the single lines to disintegrate, while the lines ruled in closer bands seemed to retain their good qualities. This disintegration finally became so marked that, as an experiment, I removed the cover and cleaned one-half of the surface of the glass by rubbing with chamois skin. The difference in the appearance of the two halves is now very marked. Above, the dense black lines remain, Below, a ragged abrasion of the surface of the glass has taken place. Above, the furrowed lines as originally formed are preserved ; below, there is a coarse scratch. It may be said that the action in this case is acci- dental and abnormal. In reply, I can say I have prepared plates which show that the particles of glass removed take four characteristic forms. (a) They appear as chips scattered over the surface of the glass. (b) They appear as particles so minute that when laid upon a windrow and forming an apparent line, they cannot be separated under the Microscope. (c) They take the form of filaments when the glass is sufficiently tough for them to be maintained unbroken. (d) They take a circular form. I regret that three of the most striking specimens were broken in mounting. In one a perfect line about 1/30,000 of an inch in width was formed with a clear space between it and the groove cut by the diamond. There was not a single break in these filaments from beginning to end, but at nearly equal intervals of about 1/100 of an inch half-knots were formed similar to those formed in a partially twisted cord. By rubbing the surface of one end these fila- ments were broken up. For the most part they assumed a semi- circular form, but some of them maintained their thread-like form and became twisted together in the most intricate fashion. In the third specimen, which was broken in mounting, the glass removed took a spiral form like the spiral chips from steel when ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 129 turned in a lathe. A projecting crystal of the diamond caught these spirals and carried them unbroken to the end of each line, leaving them a tangled mass of threads. Hven after they were protected by a cover- glass cemented to the surface, many of these spirals remained intact. Judging by the difference in focus of the various parts, the height of the mass, before the plate was covered, must have been 1/500 of an inch. The same ruling crystal may produce smooth lines or either chips or threads, according to the motion of the diamond, as may be seen by examination of the accompanying rulings In these plates one-half of the lines of the bands are ruled by a forward motion and one-half by a backward motion of the diamond. Chips may be formed in ruling bands of very fine lines, as illustrated in the bands of lines 24,000 to the inch. It must not, however, be supposed that lines of the best quality always present the appearance described above. While it is exceed- ingly rare that lines appear as well after the surface of the glass has been rubbed as before, many instances have occurred within my experience in which the difference, especially in fine lines, was not particularly noticeable. According to the limited evidence at hand, the coarser lines of Nobert’s bands present some of the characteristics which I have described. I have restored two of these plates, in which the lines had become nearly obliterated by some kind of condensation under the cover-glass. In one the quality of the lunes was not much affected by the operation of cleaning, but in the other the dark gloss which characterizes the heavy lines of nearly all of Nobert’s plates was entirely destroyed. The finer lines, however, were much less affected than the coarse ones. Lines of the character thus far described are evidently unsuited to the ordinary work of the microscopist. It is my experience that lines which are the most symmetrical in form and the most beautiful in appearance are produced indirectly rather than by the direct action of the diamond in cutting a groove in the glass. They can be protected to a certain extent by a cover-glass, but they are liable to undergo changes which will affect their original structure. Hxcept for purposes of investigation, therefore, there is no advantage to be gained by ruling lines of this character. Three conditions must be fulfilled in the production of lines having a per- manently good character :-— 1. The glass must be tough. There is a marked difference in the character of the filaments produced, and, to a certain extent, of the lines themselves, yet the conditions under which the lines in the series of plates illustrating this paper were ruled were the same in nearly all of the plates —i.e. the same diamond was used, its setting re- mained unchanged, and there was no change in the pressure of the diamond upon the surface of the glass. I may add also, that I have in my collection several other plates which were ruled espe- cially to test the question of the requisite quality of the glass. They all agree in giving evidence that glass of a given quality will always yield lines of nearly the same quality—-the ruling crystal remaining the same and in the same position. Ser. 2.—Vo.. IV. K 130 SUMMARY OF CURRENT RESEARCHES RELATING TO 2. The greatest difficulty encountered in setting a ruling crystal is to obtain one which will rule lines of the required quality which will retain their form after the surface of the glass is rubbed. The erystal with which nearly all the plates of this series were ruled was only obtained after a search continued at intervals through several weeks. Sometimes a diamond which will rule good light lines will not produce good heavy lines, and vice versd. According to my experience it is better to have a special diamond for each class of line desired, though the diamond with which the present series of plates was ruled seems well adapted to every kind of work required, except, perhaps, the production of the finest bands. An examination of plates illustrates the wide difference in the character of lines ruled with the same diamond, after the edges of the ruling crystal have been worn smooth. In one there are two sets of lines, side by side, in one of which the surface has been rubbed, and in the other of which the lines have been left undisturbed. The difference is very marked. It may be said here that the surface of a ruled plate should always be cleaned by rubbing in the direction of the lines only, never at right angles to the lines. It will often happen after sharp rubbing that the lines appear ragged, when the difficulty is that the chips have not all been removed from the grooves, Rubbing with Vienna lime, moistened with alcohol, will usually complete the cleaning satisfactorily. 3. After a crystal has been found which will fulfil the con- ditions of producing a line which will bear cleaning, there still remains a difficulty which will only be revealed after the lapse of considerable time. This is well illustrated in one plate in which the lines were as perfect as could be desired for several days after they were ruled. The lines of the band are now completely broken up. Evidently they were in a state of strain, which finally became so great that resistance to rupture became impossible. This, how- ever, is an extreme case. Generally the lines simply enlarge at certain points. Usually the termination of the enlargement occurs at irregular distances along the lines, and it is nearly always very sharply defined. The most curious action of this kind which has ever come under my notice is where the lines have broken up into a form something like the strand of a heavy rope. The process of setting a diamond is as follows: The holder has the means of adjustment in three planes: (a) an adjustment in a horizontal plane; (b) an adjustment in a vertical plane; (c) an ad- justment in a plane at right angles to the ruled lines. It is my practice to begin by giving the knife-edge of the diamond consider- able inclination to the line of motion of the ruling slide. I then rule a series of single lines at different known angles of inclination, care being taken to pass the line of parallelism. An examination of the character of the lines thus ruled will enable one to determine within narrow limits near which one the knife-edge is set parallel with the slide. After a fair line has been obtained in this way a sharp crystal is generally found by tilting the diamond in a vertical plane, though it will often be found necessary to make the third adjustment men- ZOOLOGY AND BOTANY, MICROSCOPY, ETC. ‘ 131 tioned. Sometimes the cutting crystal is lost after ruling a few lines, but generally good results can be obtained after a constant service of weeks, and even months. A crystal is lost either by being broken off or by being worn out. When a crystal has been lost it need not be concluded that the diamond needs sharpening. It is only necessary to find a new crystal, an operation requiring patience rather than skill. It should be stated, that while this theory of individual cutting- crystals seems to be the true one, I have never been able to detect them by an examination with the Microscope. It is only by their behaviour that their existence can be recognized. One of the most severe tests of the ruling qualities of a crystal consists in producing, without fracture, heavy lines which cross each other at a small angle of inclination, and which will receive graphite without interruption of continuity at the intersection. Lines ruled at right angles and forming small squares afford a better test than parallel lines. In one plate presented the curved lines formed by the intersection of straight lines are nearly perfect in form, and they hold the graphite quite as well as the original lines. In another plate I have attempted a representation of the nucleus of a comet. The filling is not quite as perfect as in the other plate, but this is due to the quality of the glass. Attention is called to the granular struc- ture under a moderately high power. I have found rulings of this form to be an excellent test of the quality of the glass required for receiving the best lines. In general, the first filling of the lines is the most perfect. One plate affords an illustration, exceedingly rare, of lines which receive the lines equally well after repeated fillings. Lines as fine as 50,000 to the inch very readily receive the graphite. The limit beyond which it seems impossible to go may be placed at about 100,000 to the inch. A few words may properly be added here with regard to the pro- tection of ruled lines. When lines are formed by a true groove in the glass, it is better that they should remain unprotected. But when the lines are formed in the manner illustrated by the plates of this series, the quality of the lines in the end is pretty sure to deteriorate whenever there is an actual contact of the cover-glass with the slide. I have made serious efforts to overcome this diffi- culty, but with only partial success, Slides mounted with gutta- percha rings generally remain in good condition for a long time, especially if, after expelling the air as far as possible by heat, a ring of white wax cements the rim of the cover-glass to the slide. But even with this precaution there is no certainty of final preservation. If it should be found that the brass slides of this series are convenient in manipulation, their adoption can be recommended, since they entirely obviate this difficulty. They are made in the following way:—A hole having been made in the centre, a flange is left 1/200 in. in thickness. The cover-glass is then cemented to the surface of the brass, and the rulings are made on the under side. The protection is made by dropping upon the ledge of brass a rather thick circle of cover-glass, which is held in position by a circular brass wire. K 2 132 SUMMARY OF CURRENT RESEARCHES RELATING TO After this digression, I return to the consideration of the credi- bility of Mr. Fasoldt’s claim that he has succeeded in ruling lines — _ 1,000,000 to the inch. At this point it is only fair to say that until recently I have shared in the general incredulity with which Mr. Fasoldt’s claim has been regarded. Indeed, I still think he has placed the limit just a trifle too high. But if the limit is reduced one-half, I am by no means sure but that it may be reached. Possibly it may have been already reached. But what evidence have we that it is possible to see single lines of this degree of fineness, granting that it is possible to produce them? The answer to this question involves another inquiry, viz. has the Microscope reached its highest visual possibilities ? Here again it is necessary to draw a sharp distinction between visibility and resolution. In the matter of limit of resolu- tion it must be admitted that little or no progress has been made since the resolution of Nobert’s nineteenth band. The distinguish- ing feature of Nobert’s lines is a certain boldness which enables them to be photographed, and it is to photography, supplemented by the statement of the maker, that we owe the certainty of the resolution of the nineteenth band. But all attempts to go beyond this band, even with Nobert’s later plates, have proved failures. I cannot learn that any one has yet succeeded in photographing a Fasoldt plate as high as 100,000 to the inch. Certainly various attempts which have been made with bands of my own ruling higher than about 70,000 have not been successful. There are several Nobert plates of the new pattern in this country. They run as high as 240,000 lines to the inch,* but who has gone beyond the number of lines in the nineteenth band? With great respect for the honest belief of several micro- scopists who claim to have resolved Fasoldt’s bands as high as 152,000 to the inch, I must yet hold to the opinion that in no case has the resolution been proved by a test which will be generally accepted by microscopists. ‘There is one test, and only one, which is absolutely decisive—viz. the one originally proposed by Nobert, that of ruling a definite number of lines in a band of given fineness, and keeping the number secret until the microscopist could give the correct count, not merely in one instance but in several. Even here we must depend upon the honesty of the maker in revealing the correct count. Has the correct count been made in any Fasoldt plate as high as 100,000 to the inch? I think not. Has it been done with any band of my own ruling of the same degree of fineness? No. Let us marshal the evidence pro and con, offered by experience. (a) Mr. Fasoldt’s finest bands present a perfectly smooth and uniform surface. They have well-defined limits, and the width of the bands is what it should be by the number of lines claimed to be ruled. (b) According to present experience single lines can be ruled * The highest is 1/20,000 of a Paris line, i. e. 224,000 to the English inch.— Ep. J.R.MS. + Mr. E. M. Nelson claims to have resolved the next finest band to the 19th, viz. the 11th band of the latest 20 band plate, the lines of which are at the rate of about 123,000 to the inch.—Eb. J.R.M.S. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 133 several degrees finer than I have been able to detect under the Microscope. About four years since I sent to Prof. J. Edwards Smith a ruled plate with a statement of the number of bands, accom- panied with a description of the same. Soon after I received a letter from Prof. Smith, saying there must be some mistake in the descrip- tion, as he was unable to find two of the bands, I replied that the bands were certainly ruled, and that I thought I could convince him of that fact. I therefore requested him to re-examine the plate with the greatest care, and if he was still unable to find the bands to return the plate to me. After a vain endeavour to discover them the plate was sent to me. I removed the cover, filled the lines with graphite, remounted the slide, and returned it to Prof. Smith. Not only had the invisible bands become visible, but the separate lines, with an interlinear space of 1/80,000 in., were easily seen. Now when Prof. J. Edwards Smith, an acknowledged expert in the manipulation of the Microscope, is unable to find lines which are really in the centre of the field of the Microscope, I suspect that other observers may find a similar difficulty. Among the plates presented is one series which were ruled to illustrate the possibility of producing lines which really exist, but which are invisible under the Microscope. On one plate there are two sets of lines, one set on the slide and the other on the under side of the cover. Between the bands, 10,000 and 24,000 to the inch, the entire intervening space is filled with a continuous series of bands, 24,000 to the inch. I have not been able to see the lines of the last band. In another plate there are a series of bands containing twenty-one lines each, the entire linear space being 1/2000 in. The first eleven lines are ruled with a forward motion of the diamond, and the second ten lines are ruled with a backward motion. The last two bands are preceded by heavy finding lines. Hach of the last three bands is followed by bands 24,000 to the inch. I think it will be found difficult to see the lines of the last two bands under any illumination at present in use, and yet I am confident that the lines exist. I found my belief upon two bits of evidence: First, the pressure of the diamond upon the glass was sufficient to produce the lines. With considerable less pressure there would still have been a constant contact between the diamond and the glass. Second, I saw them ruled through the sense of hearing. When a diamond does its very best work it produces a sharp, singing tone, which is audible at a distance as great as twelve inches. This singing tone I distinctly heard for every line ruled. It is even more marked in ruling the finest lines than in coarse ones. I have two singing diamonds, or rather two diamonds with singing crystals, and these two are the ones with which I have done my best work. The argument against the visibility of single-ruled lines which cannot be seen with the present means at command, even if within the limits of possibility, considered in a physiological sense, is in one respect a sufficient answer to the evidence offered in favour of their existence. This evidence, while not exactly negative in its character, is yet not sufficiently conclusive to be regarded as coming under the head of proof through the medium by which the 134 SUMMARY OF CURRENT RESEARCHES RELATING TO existence of any fact is attested, viz. the medium of some one of the senses. But may it not be true that we have not yet reached the fulfilment of the conditions necessary to visibility? It certainly cannot yet be safely asserted that it is impossible to see a material particle which has, in one direction, a magnitude not exceeding 1/500,000 in. Photography offers the evidence, somewhat negative in its character, that the limit of visibility is reached with lines having a width of about 1/200,000 of an inch. Lines of this width are the finest that have ever been photographed. But the most conclusive evidence against the certainty of being able to produce lines as fine as 500,000 to the inch consists in the fact, repeatedly proven in my own experience, that lines which appear to be excessively fine often have a real width two or three times as great as they appear to have, as has been proved conclusively by filling the lines with graphite, which brings out the real limit. This phenomenon will come up again in connection with the subject of resolution. I have already stated my belief that the limit of resolution has ‘been so nearly reached that, though it is quite possible under a com- bination of favourable circumstances to obtain a resolution a little beyond 113,000 to the inch, the uncertainty which must always attend observations of this character is so great that the certainty of resolu- tion cannot be safely asserted. In consideration of this uncertainty, and of the fact that so little progress has been made in resolution compared with the recent advance in the construction of objectives, I beg to propose as a test the visibility of single-ruled lines in place of the resolution of these lines in close combination. Instead of bands of lines of the Nobert pattern, I propose a series of bands, each having the same interlinear unit, but with the lines of each successive band finer than those of the preceding band. The space between the lines should not be so great as to interfere with their easy detection, nor so small as to require any effort in resolution. One micron () is a convenient unit. A heavy line should precede the band, in order to facilitate finding it. According to my own experience there are four facts which must always throw grave doubt upon any reported case of difficult resolution :— 1. It is well known that by the manipulation of the light, every other condition remaining the same, it is possible to vary the apparent number of lines in a given band of coarse rulings. Can any one offer a reason why there should not be the same difference with bands of fine lines closely ruled ? 2. I have many times ruled bands of lines with the interlinear spaces distinctly marked, but in which each line was in reality con- siderably wider than the space between the lines, as I have proved ~ by extending single lines beyond the others and filling them with graphite. The only explanation of this singular fact which I can suggest is that the diamond may possibly cut square down at one edge of the line and for the remainder of the line produce only an abrasion of the surface of the glass, which is so slight as not to interfere with throwing up a furrow upon the remaining portion. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 135 3. Lines of a given depth appear finer when closely ruled in bands than they do in single lines. i 4. Tadd another observation with some hesitation, since I have not been able to prove its truth beyond peradventure. I have often, but not always, found that when single lines, apparently invisible, are placed in close combination in bands, they not only form a visible band, but a band capable of apparent resolution into separate lines. Can any one offer a reason why we can see in combination what we cannot see as separate parts? Of course I shall be at once reminded by the astronomer that it is much easier to pick up a cluster than to see scattered stars of the same magnitude. But when it is once found, the separate stars composing it are no more easily seen than stars of the same magnitude more widely scattered. I offer this observation in a tentative way, since it has, if true, an important bearing upon the question of the ultimate limit of resolution. Among the accom- panying plates is one that illustrates the statement here made. This plate consists of a series of bands, 12,000 to 24,000 to the inch, each preceded by a heavy finding line. The lines of each successive band are finer than the preceding. The last two bands were ruled with the same pressure of the diamond as the fourth band preceding. The intervals at which they were ruled are 1/80,000 and 1/200,000 in. I do not by any means vouch for the existence of the separate lines, yet the bands are smooth, and there is a distinct difference in the appearance of the two halves of the 80,000 band, the first having been ruled with a forward and the second with a backward motion of the diamond. The corresponding single lines of the fourth band pre- ceding are wholly invisible. This plate seems to show that the visibility of the lines in bands depends somewhat on the narrowness of the interval between the lines, since the lines of the same degree of fineness with an interval of 1/24,000 in. cannot be seen. It is obvious that this whole question of resolution needs the most careful consideration and investigation, since it bears an in- timate relation to the limit of visibility of single particles of matter. Mr. Hitchcock, in a recent number of his ‘Journal, has made the claim that resolution has to a certain extent ceased to be a test of the quality of an objective. I suspect that this claim will be found to have some foundation in fact. For the last ten years we have only the assertion of resolution, without doubt honestly made, but yet unaccompanied with the proof. It is time that the proof should accompany the assertion. I insist that simple vision does not afford the required proof. Now we must face this question as honest inquirers after truth. There is a limit which theory places to resolution with objectives of given resolving power, not to visibility, as has been frequently stated. Before we can safely assert that observation has gone beyond theory, we must be prepared to offer evidence which can be placed upon record, can be discussed deliberately, can be weighed impartially in the balance with counter evidence, and can still stand unimpeached. Do you say that this is hardly worth the trouble? I reply that the issue here raised comes to the surface in one form or another at almost 136 SUMMARY OF CURRENT RESEARCHES RELATING TO every point in physiological and pathological investigations. It will do no harm to recall the number of times it has at this meeting stood as a sentinel at the entrance to the temple whose mysteries we are seeking to explore. Has not the question so tersely put by Dr. Gleason at the Elmira meeting of this Society, ‘Do we see what we see, or don’t we see what we see,'or do we see what we don’t see?’ been the stopping place of more than one important issue raised at the meeting? I hope I do not need to say that I have no personal ends to serve in an inquiry in which I happen to be a personal factor. Let us then have a test which will for ever set at rest this vexed question of resolution. I submit for your consideration the following outline of a test which I venture to think will be sufficient and conclusive. Let Mr. Fasoldt rule three plates under as nearly the same conditions as possible, except in the number of lines in the different bands of each plate. Let him label each plate and accompany it with a full descrip- tion of the number of lines in each band. Let these plates be sent to any gentleman in whom the great body of microscopists have con- fidence as eminently qualified to conduct an investigation of this sort, such as Prof. H. L. Smith of Geneva, or Col. J. J. Woodward of Washington. Let whoever receives the plates remove the labels of Mr. Fasoldt, and put in their place labels whose signification is known only to himself. Then let the gentlemen who think they have resolved 152,000 lines to the inch take the plates, make their count of the lines in each band, and send in their report. Let the plates also be photographed, and let the number of lines be counted ; then let the results of these investigations be published. If all substantially agree in the count, this will end further discussion. The limit of visibility of single particles of matter under the Microscope bears an intimate relation to the limit of naked-eye visibility. My attention was first called to the smallness of this limit by an accidental circumstance. I had ruled a micrometer upon a thin cover-glass consisting, as I supposed, of moderately coarse lines. After several vain attempts to discover traces of the lines ruled, I chanced while holding the glass at a certain angle with respect to the source of light to breathe upon it. At the instant the film of moisture was passing off, I was surprised to be able to see all the lines which were ruled, 100 to the inch, with the greatest distinctness. I then carefully filled the lines with graphite, when they were, after the closest inspection, found to be as fine as any I have ever ruled. According to the nearest measurement I could make, their width was about 1/6 of a micron. Repeated observations gave in every case satisfactory evidence of visibility. In order to ascertain what effect the thickness of the glass might have upon the visibility, the cover- glass was lightly cemented to a glass slide with guttapercha, when it was found that the lines were by no means as distinctly visible as before. The cover was then removed, when the original obser- vation was easily confirmed. The lines of this plate were readily seen by Professor Pickering, and by several assistants connected with the observatory. Unfortunately the glass was broken in an attempt to mount it upon a brass slide, While it is a simple ZOOLOGY AND BOTANY, MICROSCOPY, ETC. aif matter to rule lines which are easily visible by the unaided eye, especially in sunlight, having a width not exceeding 1/50,000 in., I have never since succeeded in obtaining a plate quite as good as the one described. Clearly the ruling crystal had been broken off before this particular plate was ruled, and, as often happens, a minute and delicate crystal remained, which produced the lines which were really traced. In the course of subsequent experiments I found that while the visibility was increased by the film of moisture, exceedingly fine lines could be seen without this aid to vision when the proper angles of inclination to the source of light are obtained. ‘To get the best results the ruled surface should have an angle of about 15° with the source of light, and the lines themselves should have nearly the same angle of inclination. Everything depends upon getting the exact angles of inclination required. More striking results are obtained by sunlight than by artificial light. Highly polished metals, especially tempered steel and iridium, yield better results than glass. I will not undertake to say how fine lines traced upon metal can be seen, but I suspect that the limit of naked-eye visibility is far beyond the capacity of ruling. I have a plate of highly polished and nearly pure iridium upon which there are traced a series of lines which are dis- cernible by the eye in sunlight, but which I have never yet been able to see under the Microscope by direct light. Yet these lines are easily seen with a low-power objective under certain conditions.j I do not propose to offer any theory to account for the facts which I have observed, not even the one which would naturally be the one first suggested—viz. that of visibility by reflection. I admit that the apparent width of the lines would be increased if the real and reflected lines could be seen side by side. It can be easily shown that the lines in one of the accompanying plates are visible under conditions in which it is impossible for reflection to take place. For the present I content myself with stating the facts of observation illustrated by the ruled plates by which these observations can be repeated. I close this paper with the suggestion that the increase in the efficiency of the Microscope will probably come from the better manipulation of the light under which an object is viewed. At present the unaided eye is a not very unequal competitor of the Microscope in the matter of simple vision. In fact, there are certain phenomena connected with this question which can be better studied by the un- aided eye than under the Microscope. I believe it to be possible to see under the action of sunlight what cannot be seen under any objective. There has been produced upon my ruling-machine, upon a polished surface of tempered steel, a band of 10,000 lines, cover- ing a space of 4 inches. I have tested the equality of the spacing for aliquot parts of a revolution of the screw in every possible way by direct measurement. Other observers have done the same thing, [ can hardly be wrong in the assertion that the spaces indicated by even tenths of a revolution are exactly equal as far as any tests of direct measurement can be applied. Yet, by holding this bar in a certain position with respect to the source of light, the limits of each revolu- 138 SUMMARY OF CURRENT RESEARCHES RELATING 'TO tion of the screw can be distinctly seen. These waves of light and shade indicate an error which can be seen by the unaided eye but which cannot be measured with certainty. Finally, if the visibility of ruled lines is so erroneously increased by the position which they occupy with respect to the source of light, why may not the visibility under the Microscope be increased in nearly the same proportion by some mechanical device which shall enable the observer to find exactly the proper angle of inclination at which the light should be thrown upon the object in order to secure the best possible result ?” Prof. Rogers, in the discussion on a paper by Dr. G. EK. Blackham on the Relation of Aperture to Amplification, also said * “'The whole thing depends on the question Can we compute resolving powers? I will not say that we cannot, and I have my doubts if we can. I question the truthfulness of the formula that is used in the computation. My confidence in it was shaken some time ago, when in the measurement of some plates I found errors of 1/40,000 in. I think that the formula is true, so far as it goes, but it does not tell the whole truth. There are conditions that affect it. Take, for instance, Bayard’s formula for refractions. It is affected by the atmosphere and temper- ature. Now, Ido not say that the two formulas are analogous; I use Bayard’s only as an illustration of what may occur. My position is this: Take what we have as a basis of investigation, and go ahead to ascertain the truth. There is a great sea for exploration in the question.” Test-Diatoms in Phosphorus and Monobromide of Naphthaline.+ —Canon BE. Carr thinks those who are interested in the resolution of the more finely marked diatoms, and who have seen or heard of the magnificent image of Surirella gemma, mounted in phosphorus, shown by Mr. J. W. Stephenson at the Society’s meetings and conversazioni, with a Zeiss’ oil-immersion 1/8 objective and his own catoptric illuminator, will be glad to learn that Moller now supplies some of the more difficult test-objects mounted in highly refractive media. Having recently purchased a slide of Amphipleura pellucida mounted in phosphorus, and one of Surirella gemma mounted in monobromide of naphthaline, he gives the result of his examination of them. The resolution of the hemispherules on the latter was not remarkable, being much the same as that obtained ona slide of the object mounted dry. The resolution of the former, however, was all that could be desired with the means at command, and contrasted favourably with anything he had seen before. Previously, with a Powell and Lealand’s water-immersion 1/8 objective, and Wenham disk illuminator, he had seen the striz very faintly shown on a balsam-mounted slide. Much better resolution had been effected on a dry mount by a Powell oil- immersion 1/25 objective, and their achromatic condenser. But even this result was not to be compared with that obtained on the phosphorus mount. Using Powell’s oil-immersion 1/12 objective (N.A. 1°48), and their oil-immersion condenser, the strie came out * Loc. cit., pp. 227-8. + Engl. Meeh., xxxviii. (1883) p. 280. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 139 remarkably clear and sharp, and, though not distinctly broken up into dots, gave apparent indications of a want of continuity. It would be interesting (he adds) if other observers who possess large- angled object-glasses, and corresponding means of illumination, would give their experience in regard to the new slides of these difficult but fascinating objects. _ Microscopic Test-Objects.*— Under the above title Mr. E. M. Nelson replied to Canon Carr as follows :—“ Having worked at these objects for some years, and having also kept pace with the times in objectives and apparatus, I will, in answer to Mr. Carr’s request, give the results of my experience: Ist, the total abolition of oblique illumination if one wishes to see the true structure of an object; 2nd, object mounted dry on cover. I use a Powell achromatic condenser, accurately centered to the optic axis. ‘The edge of the flame of a paraffin lamp, with 1/2 in. wick, exactly focused on the object, without bull’s-eye or mirror. This illumination, with a Powell oil 1/12, N.A. 1:48, easily resolves A. pellucida, dry on cover, with direct light—i. e. without slot or stop. If S. gemma is examined by this means, the hemispherule theory is at once exploded, and the true structure (which is far more beautiful) is revealed. It is something like a most delicate skeleton leaf. This, however, is very difficult for a beginner. The P. formosum is, perhaps, the best one to try first. Work away at that until the hemispheres, which are so easily seen, give place to a square grating! To see this, with 21/4, N.A. °74, will severely test the lens and the observer's manipulative skill. A coarse N. lyra and a Try- blionella punctata both have square apertures, and are very easy. N.B.—If the objective is much out of correction, the square apertures will blur round. The next one to try is P. angulatum. In this a fracture should be distinctly seen to pass through the apertures. The apertures will take a rose tint if the glass is properly corrected. It is manifestly absurd to test an objective by a fine diatom seen with oblique light, for only a small portion of a narrow marginal zone of the objective is used. The central, and by far the more important, part of the glass might be stopped out. By the central illumination, however, the whole of the objective is used ; the centre by the dioptric beam, the margin by the diffraction encils. In former days one used to hear this sort of thing said: ‘This 1/12 is a beautiful diatom glass.’ ‘This 1/10 is splendid on Podura, but not good at diatom resolving. (What a fine thing for the opticians! One had to buy two glasses, one for Podura and one for diatoms.) The explanation is very simple: for Podura a glass must be good in the centre, and for diatoms, with oblique light (the only light used in those days), good in the marginal zone. So then the 1/10, which was good for Podura, and the 1/12 for diatoms, could neither of them have been thoroughly corrected from their centres to their margins. I have a glass in my collection which is very fair on Podura when the screw-collar is in ono position, and also is a * Engl. Mech., xxxviii. (1883) p. 324. 140 SUMMARY OF CURRENT RESEARCHES RELATING TO good diatom resolver with its collar in another position; but when all its zones are tried at once, by the direct illumination, it utterly breaks down. With regard to A. pellucida, the strongest resolution is obtained with Powell’s vertical illuminator. The long striz can only be seen by this method. Spurious longitudinal striz may be easily seen ; but the true lines are very difficult, and may be estimated to be 120,000 to the in. at the lowest. The transverse I have counted repeatedly, and find them, in Van Heurck’s specimens, very constant at 95,000 per inch. The best picture of the trans-strize is obtained with oil-immersion 1/12, N.A. 1°48, or oil-immersion 1/25, N.A. 1°38, and Powell’s oil- immersion condenser, used dry, with single slot, edge of flame direct, valve being dry on cover. The lowest angled glass with which I have seen the transverse strive, is a water-immersion 1/16, N.A. 1:08, and the lowest power 1/4, N.A. 1-17.” In repiy to a letter from “ Monachus” * inviting Mr. Nelson to state how he came to recognize that oblique illumination must be entirely abolished in favour of central, and that by so doing we shall see the true structure of the object, Mr. Nelson wrote : ,—“ I began to realize the uselessness of oblique light for the determination of true structure during a lengthened examination of a Nobert’s 19-band plate. I was much struck by the appearance of a single line of the first band, when viewed by an oil-immersion N.A. 1°25, illuminated by a large angled cone of direct light. The groove which the diamond had ploughed in the glass was most distinctly seen, and along the sides of the groove there were places where the chips of glass had flown off. With oblique light all this was lost; the line appeared as if it had been painted on the surface of the glass. This showed me that if definition was wanted direct light must be used. I do not intend for one moment to affirm that a higher band of Nobert can be resolved by direct than by oblique light ; but this I do say, that the ultimate structure of a diatom can only be demon- strated by direct light. No microscopist in the present day would uphold the theory that the ultimate resolution of the P. angulatum was six sets of lines or grooves, inclined at an angle of 60° to oneanother. Buta similar view of it was held in Quekett’s time, for in the frontispiece of his book there is a beautiful engraving of it, exhibiting diamond-shaped marks all over it; a false conclusion, the result of oblique light. Neither will any one insist that the ultimate resolution of the N. Rhomboides is represented by two sets of lines, at right angles to one another, a picture produced by the employment of two beams of oblique light. In the days of Griffith and Henfrey they got beyond that, and dotted the Rhomboides. It is quite natural to expect that with the increase of aperture and the improvement in objectives there should be simultaneously a development in the resolution of the diatoms. One misses, too, with oblique light, all that beautiful tracery inside the hexagonal * Engl. Mech., xxxviii. (1883) p. 341. + Ibid., p. 386 (8 figs.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 141 areolation of the Coscinodisci, which can only be seen by direct light ; for with oblique light the blur of the hexagonal structure blots out the fine markings. When we come to the very finely-marked diatoms, such as A. pellucida and some of the Nitzschiw, we must be content with lines, by oblique light, until we can get sufficient aperture to enable us to see the ultimate structure.” “ Monachus ” rejoined as follows: *—“ I am obliged to Mr. Nelson for his reply to my letter, as it leaves no room for ambiguity as to his views. It is not of course my object, in occupying your space, to simply engage in a personal controversy with Mr. Nelson, and I therefore leave, for the moment at any rate, many points in his letters in regard to which he is mistaken, such as the statements about the two beams in the case of N. Rhomboides, the lines and dots he figures, &e. My object is to prevent your readers being misled on the cardinal statement of Mr. Nelson that he (or any one else) has seen the true structure of Surirella gemma, or any similar diatom. When this is seen we shall have reached the millennium of microscopical observa- tion—how far we are from that day no one can tell, but it is certain we have not reached it yet; and in representing what he saw as the ‘true structure,’ Mr. Nelson was but falling into the same error as the old school of microscopists whom he criticizes. I will first quote Mr. Nelson’s statement verbatim :—‘If S. gemma is examined by this means, the hemispherule theory is at once exploded, and the true structure (which is far more beautiful) is revealed. It is something like a most delicate skeleton leaf.’ Why S. gemma is beyond the reach of any such determination of its true structure, it is the object of the succeeding paragraphs to show. When rays emanating from a luminous body are transmitted through any structure, which by its opaque, semi-transparent, or refractive constituents prevents the continuous propagation of the luminous waves, the rays cease to pass through in straight lines, and each pencil is split up into a conical pencil of rays, which are dis- tributed round the course of the incident pencil, and which vary very much in the extent of their deviation. When the elements of the structure are considerable multiples of a wave-length, that is, when they are relatively large, the spread of the diffracted rays is limited; but when the elements are only very small multiples of a wave-length, that is, when they are very minute, the diffracted rays are spread out very widely. Most microscopists are by this time familiar with the practical effect of the diffraction-spectra under the Microscope, and have seen the experiments which show that the same diatom will give numerous very different images according as we admit all or some only of the diffraction-spectra. By stopping off successively the seven spectra, ~ for instance, of P. angulatum, we get as many different structural appearances—aindeed, no less than nine different sets of lines may be * Engl. Mech., xxxviii. (1883) p. 431 (1 fig.). 142 SUMMARY OF CURRENT RESEARCHES RELATING TO displayed on this diatom, according as we admit or exclude particular sets of spectra. The results obtained from this manipulation may be summarized in three propositions :— (1) The same structure will give different images when the diffraction-beams are made different. (2) Different structures will give the same image when the diffrac- tion-beams are made similar in each case. (8) (the proposition which is most pertinent to our present subject). The microscopic image of a structure is never in perfect accordance with its actual composition, or true structure, unless the whole of the diffraction-pencil is admitted to the Microscope; or, in other words, the image is always more and more dissimilar from the true structure in proportion to the greater number of diffraction-pencils which are excluded from the Microscope. The diagram will serve to illustrate the practical application of the last proposition to the examination of diatoms. If the structure is ‘coarse, the diffraction- Fie. 26. beams will all be included within a small space around the central pencil (the inner circle of the figure), and in this case an objective, even of limited aperture, will receive them all, and we shall have an image of the true structure. If the object is finer, the limited aperture will not be sufficient to take up all the dif- fraction-pencils, but a larger aperture (the middle circle of the figure) will. Still more minute structure will require a still larger aperture, as is shown by the outer circle. Now the elements of S. gemma are of such fineness that they far surpass the limits of any aperture that we are able to obtain at the present day. Aperture is limited by the refractive index of the glass of which the objectives are made, and that of the immersion fluid, cover-glass, and slide, and hitherto we have not been able to obtain more than 1:47 N.A. out of a possible 1:52. An aperture even of 1°52 would take up but a part of the diffraction-beams to which the structure of S. gemma gives rise, and, therefore, with our widest apertures it is impossible for us to see its true structure. I need not give the figures of the calcula- tion here ; but the fact is that to see the true structure in reality, we should require objectives, slides, and immersion fluids far surpassing in refractive index any substance hitherto known to exist in nature. To quote Prof. Abbe: ‘All speculations as to the true structure of even P. angulatwm, so far as they depend on microscopic vision, are mere phantoms, castles-in-the-air. No human eye has ever seen, ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1438 or will ever see, the complete diffraction-spectra arising from a structure of this minuteness, nor will any Microscope ever show an enlarged copy of it, so long as the spectra cannot be observed in a medium of at least 5:0 refractive index, and by an objective of 5-0 N.A., which, as far as our present knowledge goes, is an impossibility. The Microscopes of the present day admit relatively a small central portion of the whole diffraction-pencil of the valve—i.e. the incident beam and the six spectra of the inner circle. But this portion is also yielded by a multitude of other objects which are endowed with an alternation of superficial or internal molecular structures which cross each other in two different directions at an angle of 60°. Such structures may be formed in various widely different ways; it may be by rows of spherules or other prominences of any shape whatever ; rows of internal vacuoles of any figure, or the mere internal alterna- tions of molecular aggregations within a perfectly transparent and smooth silica film. And yet all of these yield with central light the identical circular field of the angulatum valve, even to the most minute particular. But although these spectra are identical as far as the six inner spectral beams are concerned, they may be vastly different in regard to some or all of the more widely diffracted pencils which are not admitted by the objective.’ However expert, therefore, a microscopist may be (and every one knows the high point which Mr. Nelson has reached), he must not delude himself with the notion that perfection in technical dexterity enables him to determine the “ true” structure of objects whose real structure cannot be revealed with our present appliances by any amount of manipulation. The greater his own reputation in this respect, the more undesirable it is that he should proclaim such mis- leading views, to the perplexity of his less experienced brethren.” Resolution of Amphipleura pellucida by Central Light.—This has been the subject of some controversy in America. Mr. A. Y. Moore* considers the real explanation of the resolution when the mirror is central to be that the edge of the front cell of the objective radiates the light and all light reaching the bottom of the slide at a greater inci- dence than the critical angle is reflected upwards and enters the lens after having passed through the diatom. Dr. H. J. Detmersf considers this explanation to be quite untenable and the true cause to be that “the resolving rays are reflected from the (externally convex) internally concave surface of the edge of the immersion fluid.” Prof. A. Y. Moore, in reply,{ insists upon the correctness of his view and the insufficiency of that of Dr. Detmers, inasmuch as the field of view takes the colour of the metal of which the front cell of the objective is made. This would not occur if the light were reflected from the edge of the drop of immersion fluid. * The Microscope, iii. (1883) pp. 49-51 (1 fig.). Cf. this Journal, iii. (1883) p. 595. + Ibid., pp. 197-201. + Ibid., pp. 201-4. 144 SUMMARY OF CURRENT RESEARCHES RELATING TO ALBERTOTTI, G., jun.—Sulla Micrometria, (On Micrometry.) [Post.] Ann. di Ottalmologia, XI. (1882) pp. 29-30 C1 pl.). Klin. Monatsbl. f. Augenheilkunde, 1882. Anon.—The Wonders of Optics. (Inquiry for “a glass that I can see through paper or leather, and if you have one please to be kind enough to send me the price of it at once”’ ; and reply of editor, ‘‘ Punch a hole in the paper or leather.”] Micr. Bulletin, 1. (1883) p. 7. Bartow, T.—See Tolles, R. B. Bausch and Lomb Optical Co.’s new pattern ‘‘ Investigator Improved ” Microscope, and 1/4 in. objective. [Coarse adjustment moves nearly 2 in. higher—pillar heavier and higher— separable swinging tail-pieces—Objective with extra large working distance. ] The Microscope, Ill. (1883) p. 239. Bett, J. S. B.—Warm Stage and Stage Condenser for Diatomacez. [Warm stage post. Stage condenser “simply an addition of a shutter to the hemispherical lens .... similar to that used by Powell and Lealand.”’] Micr. News, IV. (1884) pp. 19-20. BLackHAM, G. E.—The relation of aperture to amplification in the selection of a series of Microscope Objectives. [Post.] Proc. Amer. Soc, Micr., 6th Ann. Meeting, pp. 33-41. Discussion, pp. 227-31. 3 5 See also Tolles, R. B. Brappury, W.—The Achromatic Object-glass, X XIX. Engl, Mech., XX XVIII. (1883) pp. 258-9 (1 fig.). BS » On Hye-pieces. es 06 (1884) pp. 401-2. Buiiocu, W. H.—New Congress Nose-piece. Patented 1883. [Supra, p. 118.] The Microscope, ILI. (1883) p. 218 (2 figs.). Also U.S.A. Patent, No. 287904, of 23rd January, 1883. C., J. A.—See Penny, W. G. Carr, E.—Microscopic Test Objects. [Supra, p. 138.] Engl. Mech., XX XVIII. (1883) p. 280. Conen, E., and Grimm, J.—Sammlung von Mikrophotographien zur Veran- schaulichung der Mikroskopischen Structur von Mineralien und Gesteinen. (Collection of micro-photographs for the demonstration of the microscopical structure of minerals and rocks.) Parts IX. and X. (conclusion). 38 pp. Plates 65-80. 4to, Stuttgart, 1883. Coun, F.—Bicentenary of Bacteria. [Calls attention to the fact that, in a letter dated 14th September, 1683, A. van Leeuwenhoek gave notice to the Royal Society that with the aid of his Microscope he had discovered in the white substance adhering to his teeth very little animals moving in a very lively fashion. ‘ They were the first bacteria the human eye ever saw.” [See also “ L.,” infra. ] Nature, XXIX. (1883) p. 154. Cort, J. B.—Determination of the Foci of Lenses. U.S.A. Patent, No. 288025, of 17th September, 1883. Coomss, C. P.—Address as President of the Postal Microscopical Society, 11th October, 1883. [On “examining occasionally the food we eat or the clothes we wear.” ] Journ. of Microscopy, III. (1884) pp. 1-7. Cox, J. D.—A new form of Microscope-stand with concentric movements. [ Post. ] Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 147-8 (1 fig.). Discussion, pp. 235-6. D., E. T.—Graphie Microscopy. [Description of coloured lithograph of Tingis Crassiochari.] Sci.-Gossip, 1884, pp. 1-2 (1 pl.). Dar.ine, S.—Micrometer. U.S.A. Patent, No. 287420, of Ist March, 1883. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 145 D., E. T.—Drawing from the Microscope. [Points out the error of B. Hobson’s suggestion—Vol. IIT. (1883) p, 725— of a semi-rotation of the stage to cure the inversion with the neutral tint reflector. Also remarks on the value of the camera lucida: “In micro- scopical work the camera lucida is merely a preliminary adjunct of limited utility in determining proportions; no graphic or perfect drawing is helped by its continued use; after affording the barest outlines and positions the instrument becomes an encumbrance, and those who are practised in its employment feel a palpable sense of relief, and breathe again, when itis got rid of, to settle down to the earnest work of direct vision from the Microscope.” ] Sci.-Gossip, 1883, pp. 265-6 (1 fig.). Dean, A.—Microscopical. [Description of a “‘micro-magic lantern” with or without camera lucida. ] Engl, Mech. XXX VIII. (1884) p. 391 C1 fig.). Dermers, H. J.—Resolution of Amphipleura by sunlight, mirror-bar central ; with letters from R. B. Tolles and A. Y. Moore. The Microscope, III. (1883) pp. 197-201 and p. 221. DickEenson.—Art of photographing microscopic objects. [The apparatus consists of (1) an inexpensive magic lantern, illuminated by a triplex petroleum lamp with the ordinary combination of lenses, and an extra tube with a small bull’s-eye condenser; (2) a Microscope, placed horizontally, without the eye-piece; and (8) a frame to hold the glass screen for focusing the image, and to receive the sensitized plate when photographing. The period of exposure is from eighteen seconds to two hours. ; Note read before Academy of Medicine in Ireland. Engl. Mech., XX XVIII. (1883) p. 279. Sci.-Gossip, 1884, p. 17. Dinner, Microscopists at. [Facetious account of a mythical dinner at which “ every article of food was carefully examined.”’] The Microscope, III. (1883) p. 233. Diprret, L.—Hin verstellbares Zeichenpult. (An adjustable drawing desk.) [Reported as from Lab. Hist. Collége de France, 1883, p. 188, instead of 1879. [See Vol. III. (1883) p. 565.] Bot. Centrailbl., XVII. (1884) pp. 62-3 (2 figs.). Eye-pieces, Report of the Committee on. [ Vol. III. (1883) p. 711.) Proc. Amer, Soc. Micr., 6th Ann. Meeting, pp. 175-7. Discussion, pp. 238-9. FiscuEer, G.—Ueber einige Versuche zur Hebung der Chromatischen Aberration dioptrischer Fernrohre. (On some attempts to remove the Chromatic Aberra- tion of dioptric Telescopes.) ' [Contains an abstract of S. Merz’s article ‘‘ Ueber Dispersionsverh4ltnisse optischer Glaser” (Vol. II. (1882) p. 565), with additional remarks. Also report of letter from K. W. Zenger on his Endomersion Objectives, ante, Vol. IIL. (1883) p. 596, and post. } ; Central-Ztg. f. Optik u. Mech., TV. (1883) pp. 265-7. Grimm, J.—See Cohen, E. Hacer, H.—Le Microscope. Théorie et Application. (The Microscope. Theory and application.) Translated from the 4th German edition with annotations by L. Planchon and L. Hugouneng. Introduction by J. E. Planchon. x. and 264 pp., 350 figs. 18mo, Paris, 1884. Hammonp, A.—Address on resigning the chair of the Postal Microscopical Society. [Account of the notes written by members of the Society on the slides circulated. ] Journ. of Microscopy, IIL. (1884) pp. 7-17. HitcGarp, Prof.—See Micrometer Scale. Ser. 2.—Vot. IV. L 146 SUMMARY OF CURRENT RESEARCHES RELATING TO Hitcucock, R.—Notes from Abroad. [Ross & Co.’s establishment and Dr. Schroder. Messrs. R. & J. Beck. Mr. Crouch. Powell & Lealand. Swift & Son. Swift’s Achromatic Con- denser (2 figs.). Swift’s Wale’s Stand (1 fig.).] Amer. Mon. Micr. Journ., LV. (1883) pp. 226-9 (3 figs.). s A new Camera Lucida. [Dr. H. Schréder’s, Vol. III. (1883) p. 813.] Amer, Mon. Mier. Journ., TV. (1883) p. 230. » The Army Medical Museum. [As to Dr. Woodward’s retirement. ] Amer. Mon, Micr. Journ., TV. (1883) pp. 236-7. es », Lesting a Microscope. [Directions for testing (1) the centering of objectives, (2) the binocular. ] Amer. Mon. Micr. Journ., V. (1884) pp. 7-8. 5 » A simple Eye-piece Indicator. Dae a [A hair attached to the diaphragm of the eye-piece and extending half-way across the field of view. | 4 Amer. Mon. Micr, Journ., V. (1884) pp. 8-9. = » Bulloch’s improved “ Biological ” stand. [Improved substage. Post.] Amer, Mon. Micr. Journ., V. (1884) pp. 9-10. » ;, Microscopical Societies. [Recommending practical demonstrations like those of the Quekett Micro- scopical Club.] ; Amer. Mon. Micr. Journ., VY. (1884) p. 16. See also Tolles, R. B. Houmes, E.—Drawing from the Microscope. [Remarks on E. T. D. supra, and suggesting that with the neutral tint reflector “he has but to turn his slide over, i.e. cover downwards on the stage, to make his outlines, and then put his slide right way up when he fills in his detail freehand.”] Sci.-Gossip, 1884, pp. 17-18. Hotmegs (O. W.) Dr., and the Microscope. [In a recent speech, in illustrating the microscopical facilities of the Harvard Medical School, he said :—‘‘ A man five feet high, enlarged to correspond with the Microscope power used, would be a mile high, would weigh 120,000,000,000 lbs., and could pick up the Boston State House and chuck it into the sea, cleaning out that ancient structure by a summary process which would put to shame the exploits of Commodus and his kind.” } Micr. News, III. (1883) p. 340. Hucounena, L.—See Hager, H. James, F. L.—The Fakir and his little Fakes. [I. Warning against using silver-plating fluid sold by street venders as it disintegrates the brass of objectives ; formula for a good fluid. II. Anec- dote of a street vender of Microscopes who showed paste eels as animal- cules in water. ] The Microscope, I1l. (1883) pp. 193-7, Kout, G.—Boecker s neuer Zeichen-Apparat nach Dippel. (Boecker’s new Draw- ing Apparatus after Dippel.) [Supra, p. 119. Bot. Centralbl., XV1. (1883) pp. 385-6 (1 fig-). L.—Bicentenary of Bacteria. [Suggests that the Royal Society should celebrate it by urging on the Government the formation of a national laboratory of hygiene. ] See also Cohn, F., supra. Nature, X XIX. (1883) p. 154. Lipricu, F.—Vorschlag zur Construction eines neuen Spectral-apparatus. (Pro- posal for the construction of a new spectral apparatus.) [Contains a description of an “ Astigmatic Mikroskop-Ocular,” consisting of two cylindrical and two plano-convex lenses, for use with a spectroscope. ] Zeitschr. f. Instrumentenk., LV. (1884) pp. 1-8 (2 figs.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 147 repay J. M. —letrusion of labour among microscopists. [ Post. ] - Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 43-5. Discussion, pp. 231-2. Matruews’ (J.) Simple Revolving Table. [Two perfectly flat wooden boards, placed face to face, the upper one turning on a pivot in the centre of the lower. The lower board should have some rubber on its under surface, or some material which will cause it to remain in position on a table while the upper one is caused to revolve. ] Amer, Mon. Micr. Journ., TV. (1883) p. 238. Micrometer Scale, A, 1882. 1. History of the National Committee on Micrometry. By R. H. Ward. 2. Report of the National Committee on Micrometry, and accompanying report of Prof. Hilgard. 3. A study of the Centimetre marked “A,” prepared by the U.S. Bureau of Weights and Measures for the Committee on Micrometry. By W. A Rogers. 4. Rules for the control of the standard Micrometer. Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 178-200. “ Monachus.”—Microscopic Test Objects. [Supra, pp. 140-1.] Engl. Mech., XX XVIII. (1883-4) p. 841 and p, 481 (1 fig.). Moorz, A. Y.—The Resolution of Amphipleura pellucida, A reply to Dr. Detmers. The Microscope, III. (1883) pp. 201-4. (See also pp. 200-1.) Nexson, E. M.—Microscopic Test Objects. [Supra, pp. 189-40.] Engl. Mech., XX XVIII. (1883) p. 324 and p. 386 (3 figs.). $0 % On the relation of Aperture to Power in Microscope Object- glasses. [ Post. ] : Engl. Mech., XXX VIII. (1883) pp. 367-8. Nony, R. J.—The Microscope in Medical Gynecolog y- [‘ For clinical microscopy no great depth of learning nor an intimate acquaintance with fine-spun theories is required, but a plain practical knowledge of the names and appearance of a few of the forms which the Microscope reveals. It is not necessary to know what everything seen in the Microscope is; it is sufficient to know what it is not. Just as it is not necessary to be an accomplished botanist to distinguish an oak tree from a turnip, or to be a deeply learned naturalist to tell a horse from a goat, so it is unnecessary to be a thorough pathologist to be able to make good use of the Microscope for clinizal purposes.”’ ] Sep. repr. from Trans. Med. Assoc. Georgia, 1883, pp. 8-10. PENNY, W. G.—Theory of the Eye-piece. J. The Dispersion of Light. II. Dis- persion of Light. Also criticisms by J. A. C. III. Spherical Aberration. Engl. Mech., XX XVIII. (1883) p. 383 C1 fig.), p. 367 1 fig.), p. 390 C1 fig.). PFAFF’S Mairoponiemeten ; Hoffmann’ s Bericht u. d. Wiss. App. a. d. L ondoner Internat, Ausstell. 1876 (1881) pp. 435-6 (1 fig.), p. 738. Priancuon, J. E.—See Hager, H. Povusen, V. A.—Botanical Micro-chemistry. Translated with the assistance of the author, and considerably enlarged by W. Trelease. [Supra, p. 91.] xviii. and 118 pp., 8vo., Boston 1884, Powe.L, Hugh, Death of. Engl. Mech., XX XVIII. (1883) p. 279, from Times, Nov. 1883 ; Sci.-Gossip, 1884, p. 17; Journ. of Science, VI. (1884) p. 51. ** Prismatique.’ ’—Object-glass working, IX. and X. Engl. Mech., XX XVIII. (1883-4) p. 296 C1 fig.), pp. 420-1. Rezner, W. B.—See Vorce, C. M. Rocers, W. A.—A critical study of the action of a diamond in ruling lines upon glass. [Supra, p. 126.] Proc. Amer. Soc. Micr., 6th Ann. Meeting, 1883, pp. 149-65. 3 Ee See Micrometer Scale. ‘Sroxes, A. C.—A Growing-cell for minute Organisms. [Supra, p. 122.] Sci.-Gossip, 1883, pp. 8-9 (1 fig.). L 148 SUMMARY OF CURRENT RESEARCHES RELATING TO StToweE.., C. H. and L. R.—A new Microscopical Journal. [‘ Science Record.”] The Microscope, III. (1883) p. 223. », Fasoldt’s Micrometers. [Micrometer which showed Newton’s rings in a beautiful manner; also a newly ruled micrometer, each alternate line being ruled longer, so that the end of each band is half the value of the band proper; that is, if the band was in the field ruled 50,000 to the inch, then the end of that band would show 25,000 to the inch. Therefore, as Mr. Fasoldt says, ‘‘ one can easily judge if there is any diffraction.’’] The Microscope, Il. (1883) p. 239: C. H.—A Microscopic Inflation. [Facetious rejoinder to Dr. O. W. Holmes’ statement, supra, as to the size of an enlarged Harvard student. } a » see Tolles, R. B. T. T.—Microscopic Test Objects. [Points out the error in E. M. Nelson’s suggestion, supra, p. 139, that ob- jectives should not be tested by oblique light.] Engl. Mech., XX XVIII. (1884) p. 386. » Relation of Aperture to Power in Microscope Object-glasses. [Reply to E. M. Nelson, supra, showing the wide difference between his figures and those of Prof. Abbe. ] The Microscope, IV. (1883) pp. 10-11. Engl. Mech., XX XVIII. (1884) p. 410. TrtLtow, D.—Microscope. U.S.A. Patent, No. 287978, of 24th August, 1883. Totes, R. B., Death of. Boston Evening Transcript, 28th Nov., 1883. Engl. Mech, XX XVIII. (1883) p. 336. Science, III. (1883) p. 726. [‘‘ Mr. Tolles has been long known for the construction of Microscopes and Telescopes of unusually short focus. He made the highest-power Micro- scope produced in America ” !] Athenzum, 1883, p. 819. Micr. News, 1V. (1884) p. 25. The Microscope, 1V. (1884) pp. 3-4 (T. Barlow); pp. 4-5 (C. H. Stowell) ; pp. 5-6 (G. E. Blackham), Amer. Mon. Micr. Journ., V. (1884) pp. 10-11 (S. Wells and R. Hitchcock). Mier, Bull., X. (1883) pp. 5-6. Science Record, Il. (1883) p. 438. we 5, see Detmers, H. J. TornesouM, A. E.—Ueber eine Vorrichtung an Mikroskoptischen zur allgemein giltigen Fixirung eines bestimmten Punktes in einem Praparat. (On an arrangement of the microscope-stage for the universal fixing of a given point in a preparation.) [Post] Neues Jahrb. f. Mineral., 1883, I., pp. 195-6. TRELEASE, W.—See Poulsen, V. A. Vorcr, C. M.—A Memoir of W. B. Rezner. Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 242-5. Wautmsuey, W. H.—Photo-micrography with dry-plates and lamplight. [Vol. ILI. (1883) p. 556. ] Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 59-64 (1 fig.). Warp, R. H.—See Micrometer Scale. Weis, S.—See Tolles, R. B. Wuitine, Saran F.—College Microscopical Societies. [Advantages of such societies, and how they can be made a success. ] Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 27-31. Discussion, pp. 225-7. Waieut, L.—Lantern and Limelight matters. [Comparative optical conditions of wick’d lamps and the limelight— Condensers—Lime-jets. | Engl. Mech., XX XVIII. (1883) pp. 343-4 (2 figs.). Zencer, K. W.—See Fischer, G. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 149 B. Collecting, Mounting and Examining Objects, &c. Mounting and Photographing Sections of Central Nervous System of Reptiles and Batrachians.*—Dr. J. J. Mason describes the methods he employed in mounting the sections from which the plates illustrating his book f were “artotyped.” “Both the brain and spinal cord were entirely separated from the body, and, with their membranes, placed in iodine-tinted alcohol until they had acquired a slight degree of consistency—from six to twelve hours. They were then transferred to a 3:100 solution of bichromate of potash, with a small piece of camphor, in a tightly corked wide-mouthed bottle, and allowed to remain until ready for cutting, renewing the solution every two weeks. The time required for the hardening process varies considerably in different animals, and this variation is more dependent upon the class of animal than upon the relative dimensions of the specimens. For example: on the same day I placed the brain of a large rattle- snake with that of a small salamander in the same bottle, and at the end of six weeks the former was ready for section, whilst the latter was not sufficiently hard until a month afterwards. By thus em- ploying the same reagent in all cases, I have been able to note constant differences in the action of both the hardening and the colouring agent, carmine. Perhaps the most striking illustration of this is furnished by the nervous centres of tailed batrachians, which, while they stain very readily, invariably require about a third more time to harden than specimens from the other orders. Specimens from ophidians stain less satisfactorily than those from any other of the classes which I have studied, while with the spinal cords of alligators, turtles, and frogs failure to obtain good results in this particular is very rare. In all cases the sections have been stained after cutting, injury from excessive handling being wholly avoided by the use of siphon- * «Minute Structure of the Central Nervous System of certain Reptiles and Batrachians of America,’ 1879-1882. Cf. iii. (1883) p. 910. + “The methods of histology have reached a perfection which is building up new departments of knowledge, and among successful pioneers in these labours Dr. Mason will always hold an honoured place for the technical skill with which he brings the reader face to face with the revelations of his Microscope, and for the sumptuousness with which his work is given to the world. No such mono- graph has previously come under our notice, for the illustrations of a difficult research leave nothing to be desired. . . . “ No words could do justice to the beauty of the plates or the value of the information they convey ; and it is not too much to regard this work as opening a new era in research by substituting knowledge of facts of microscopical structure for their interpretation by the hand of artist or author; but we can scarcely hope to see many books so beautifully illustrated. The author’s method has the merit of inaugurating a comparison of the minute anatomy of the nervous system by enabling the reader to see the structures which he has discovered as he saw them; and hence the book will always be a valuable work of reference ; and it will certainly induce others to hand on the torch of knowledge in a like excellent way.”—From Bibliographical Notice in Ann. and Mag. Nat. Hist., xii. (1883) pp. 270-4. 150 SUMMARY OF CURRENT RESEARCHES RELATING TO tubes to remove the alcohol and washings. For producing trans- parency, oil of cloves has been used, and the mounting has been done under thin, clear covers, in a solution of Canada balsam in chloroform. All the negatives have been made on glass thoroughly cleaned and lightly coated with a solution of wax and benzole, so that the collodion film, previously made adherent to thin sheets of gelatine, could be safely removed from the plate. The flexible negatives thus obtained are well adapted to the artotype process, and, as they can be indefinitely preserved between the leaves of an ordinary scrap- book, are very desirable for a series of illustrations. In making the original negatives on glass, the ‘wet collodion process, with the sulphate of iron developer, has been exclusively employed. The prints correspond exactly with the negatives, both in outline and detail. No distortion occurs as in silver printing, in which process the paper is subjected to prolonged washing, In many of the photographs the grey substance appears lighter in shade than the white substance. This appearance is due to a greater degree of transparency of the grey substance in these sec- tions, resulting from the action of the oil of cloves, followed by an increased action of the transmitted light on the sensitive collodion film of the negative, and hence by a thinner deposit of ink over corresponding parts of the positive plates from which the artotypes are printed.” With regard to the process employed, Dr. Mason says that after experimenting with various methods he found that satisfactory prints could be made in ink directly upon plate paper, and that these im- pressions were as perfect in fine detail as any of those obtained by the silver process of printing. The plates (all printed by the arto- type process) are as durable as steel engravings. “ While a photo- graph cannot often show all that can be discovered by more direct microscopic observation with a judicious working of the fine adjustment, high authority has stated, and perhaps correctly, that a good photo- graph with a low power—say from 3 to 1/2 in.—is a better means of illustrating the anatomical structure of the nervous tissues than hand drawing. Some of the plates with high powers leave much to be desired both in distinctness and tone, and in general it may be affirmed that the same defect as regards distinctness always exists, and for obvious reasons, in photographs of sections with powers much above 1/2 in. In fact it now appears to be established that immer- sion objectives can never be employed for photographing section- preparations with the success that has attended their use for blood corpuscles, diatoms, and similar specimens.” Preparing Spermatozoa of the Newt.*—G. F. Dowdeswell writes that to prepare the spermatozoa of the newt for the examination of the minute barb discovered by him, the first essential is to get them as nearly as possible in contact with the cover-glass and flat upon it; this requires some care to avoid their drying, by which they are * Quart. Journ. Micr. Sci., xxiii, (1883) pp. 336-9 (1 fig.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 151 materially altered. They may be preserved by several methods, either by treating for twelve to twenty-four hours with a concentrated solution of picric acid, a dilute solution of chromic acid, by Dr. Klein’s method with a 5 per cent. solution of ammonium chromate, by iodine, by silver nitrate, or by osmic acid or gold chloride; the latter are convenient as being quicker. He has most usually em- ployed picric acid. For staining glycerine, magenta* is the best method, as it stains all parts as strongly as desired. To show the general structure alcoholic carminate of ammonia is the most satis- factory, but it does not stain the barb deeply. Other anilin dyes have not been found to answer so well. The use of glycerine as a mounting fluid for preparations stained with any of the anilin dyes is at best troublesome, and sooner or later, in the author’s experience, the staining runs and the preparation is spoiled. Solutions of acetate of potash or chloride of calcium have not been found satisfactory, the forms, even of such resistant objects as bacteria, in some cases becoming materially altered by these re- agents. With Canada balsam, even when dissolved in chloroform or turpentine, the preparations have not been found to fade, as has some- times been said to be the case, and as we should have expected; nor, if they are sufficiently washed in alcohol and passed through oil of cloves, will they run. The risk, however, of both fading and running may be entirely obviated by using benzine as a solvent for the balsam, or by employing it undiluted and liquefied by warmth. Killing Hydroid Zoophytes and Polyzoa with the Tentacles extended. {—H. C. Chadwick recommends the polyzoon to be placed in a small beaker or clear glass bottle, and allowed to remain at rest for several hours. Now take a dipping-tube drawn out to a very fine point and charge it with absolute alcohol. Having ascertained by means of a pocket-lens that the polypides are fully extended, allow the alcohol to drop very gently from the point of the tube, which should be held just above the surface of the water. The success of the experiment depends largely upon the care with which the first quantity of alcohol is introduced into the water. After the lapse of an hour, if the polypides are still extended, a further quantity of alcohol is added until the quantity reaches 60 per cent. After passing through 75 per cent. alcohol, the specimens may be kept in 90 per cent. of the same until required for mounting. Ex- periments with alcohol upon hydroid zoophytes were not so success- ful, but Kleinenberg’s picrosulphuric acid solution § gave excellent results, The use of this reagent is attended with much less difficulty than that of alcohol. If the subject of the experiment is a zoophyte, * Magenta cryst. 1 part; glycerine 200 parts; alcohol 150 parts; aq. 150 parts; immerse the preparation in the solution for from two to four minutes, according to the depth of colouring required, and then wash. + The method is, add an equal bulk of glycerine to the aqueous solution of the anilin dye used, stain somewhat more deeply than requisite, mount on slide with cover-glass in the staining fluid, which is to be gradually replaced as the water evaporates by plain glycerine. { Micr. News, iii. (1883) pp. 333-4. § Cf. this Journal, ii. (1882) p. 867. 152 SUMMARY OF CURRENT RESEARCHES RELATING TO such as Aglaophenia pluma or Plumularia setacea, it must be allowed to remain some hours until the polypides are fully extended. Klein- enberg’s fluid must then be introduced by means of a dipping-tube. It may be allowed to flow over the specimen in a continuous stream, until the whole of the water assumes a golden yellow colour. The reagent causes instant death, so that the specimens may be transferred immediately to 60 per cent., and afterwards to 75 per cent. alcohol, allowing them to remain in each solution for some hours. Keep in 90 per cent. alcohol. From four to six minutes’ immersion in Martindale’s picrocarmine staining fluid is sufficient to stain specimens killed by either of the above methods. Mounting Pollen as an Opaque Object.*—W. Blackburn gives directions for mounting pollen dry upon the anther from which it has escaped. For collecting and drying the anthers, the flowers should be gathered when full-blown, just before they begin to fade, and the stamens then cut with fine scissors a short distance from the anthers, the latter being allowed to fall upon elean writing paper, when a selec- tion may be made with a pocket-lens of the specimens most suitable for preservation. Folding the paper without pressure, place the packet in a box, where the author lets it remain in oblivion for twelve months or perhaps two years. In the case of large anthers, such as the Lilium auratum, it may be advisable to lay them on a piece of blotting-paper, inside the writing-paper, in order the better to absorb moisture, care being taken when mounting, to remove any adhering fibres of the blotting material with a needle. Thin metal and bone cells may be used for mounting. The metal ones may be either of brass or block tin. For small anthers, such as those of Ranunculus aquatilis, the ordinary 1/2 in. brass cells are suit- able. For larger anthers, or groups of stamens and anthers, such as may be made from the Abutilon, 5/8 in. and 3/4 in. bone eells are the best. Bone is much preferable to metal for its adhesive capacity when affixed to glass, and the bone cells usually sold have their surfaces “ truer” than those of metal. For cement use ‘ quick- setting” gold size. When about to mount the anthers, paint the bottom of the cell with “matt-black,” using the turntable, so as to distribute it evenly over the glass. When the “ black” is partially dry, place the anthers upon it in suitable positions, and gently press them with a blunt needle so as to secure their adhesion to the cement. ‘The best effect will be produced when the anthers are arranged in the centre of the cell with the stamens directed on one side, as in their natural position. This, however, may be left to the taste of the mounter; and in many cases no arrangement of this kind will be required, as one or other will be found large enough to fill the cell, When there is found to be a deficiency of pollen on any of the anthers after mounting, some pollen may be taken on the point of a needle from other anthers and placed in position on the bare parts, when gently breathing upon it will fix it. * Micr. News, iii. (1883) pp. 297-9. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 158 Mounting Fluid for Algee.*—For preserving the cell-contents and the natural colour and form of desmids, volvox, and other alge, G. W. Morehouse finds a mounting fluid made as follows to act well: Dissolve 15 grains of acetate of copper in a mixture of 4 fluid ounces of camphor water, 4 fluid ounces of distilled water, and 20 minims of glacial acetic acid ; add 8 fluid ounces of Price’s glycerine, and filter. When sections of plant-stems, or other vegetable specimens, are mounted in this fluid, the protoplasm is preserved. If, in any case, it is thought desirable to inerease or diminish the specific gravity of the preservative, the proportion of glycerine may be changed. Used as above, or modified as indicated, he thinks it also a trustworthy medium for mounting infusoria and the softer animal tissues. Mounting Diatoms in Series.|—P. Francotte has applied Gies- brecht’s method ¢{ of mounting sections in series to the mounting of diatoms. ‘The slide is coated with the solution of shellac in alcohol washed over with oil of olives or creosote, and the diatoms, previously placed in absolute alcohol, arranged in order. The slide is then warmed, and the oil of cloves or creosote evaporated. Schallibaum’s process § for sections would also be available for the same purpose. Registering Micrometer-screw to the Thoma Microtome.||— Dr. C. O. Whitman gives the following more detailed description of . this screw, which we described at pp. 914-5 of vol. iii. (1883) from the original article of Andres, Giesbrecht, and Mayer, the designers of the arrange- ment for regulating its movement. This arrangement consists of a spring which, after a given number of divisions of the drum, registers to the ear and finger of the manipulator the number of micromilli- metres which the object has been raised. The intervals between the registering clicks can be varied by means of a vernier- like adjustment of the two halves of the drum, so as to equal an entire revolution of the drum, or only 1/15, 1/3, or 1/2 of a revolution. An examination of fig. 27, which illus- trates the new form of the drum, will show how the intervals are regulated. The drum is composed of two symmetrical halves, AB and A’B’, so closely opposed that the dividing line (dotted in the figure) is scarcely visible. The periphery of each half is composed of two zones of unequal radii. The large zones, B and B’, are in apposition, and together form the graduated * Amer. Mon. Micr. Journ., iv. (1883) pp. 234-5. + Bull. Soc. Belg. Micr., x. (1883) pp. 43-8. { See this Journal, ii. (1882) p. 888. § See this Journal, iii. (1883) p. 736. —__ ! || Amer. Natural., xvii. (1883) pp. 1313-4 (1 fig.). 154 SUMMARY OF CURRENT RESEARCHES RELATING TO portion of the drum. Each of the smaller zones is marked with the figures 1, 2, 83, and 15. Whenthe drum is in order for work, it rotates with the screw, which is marked g g in fig. 53, vol. iii. (1883) p. 302. The left half of the drum A B is held in position by the screw 8, and may be rotated independently of the right half A’ B’, or ,of the screw gg, by the aid of a handle which fits the holes x a a. When the half A Bis adjusted to the half A’ B’, in the manner represented in the figure, the fifteen equal parts into which the zone B is divided exactly correspond to the same number of parts in the zone B’, so that the grooves which mark these parts in one zone, become continuous with those of the other zone. Thus adjusted, the spring, which rides on the zones B B’, with a sharp edge parallel to the grooves, will give fifteen sharp clicks in the course of one rotation of the drum, the click being heard every time the sharp edge falls into coincident grooves. In order to adjust for fifteen clicks, it is only necessary to rotate A B until groove 15 becomes continuous with groove 15 of the opposite half (A’ B’). For one click in one rotation, the grooves 1, 1 must be made to coincide ; for two clicks the grooves 2,2, and for three clicks the grooves 3,3. The intervals between successive clicks may thus be made to correspond to 1/1, 1/2, 1/3 or 1/15 of a complete rotation of the drum, and the thickness of sections corresponding to these intervals should be respectively -015, -0015, _ °005, :001 mm. AcuEson, G.—Biological Study of the Tap Water in the School of Practical Science, Toronto. [Methods of examination—Diatomacese—Desmidiacee—Phycochromaceze —Schizophyte—Protozoa— Vermes—Arthropoda. ] Proc. Canad. Institute, I. (1883) pp. 413-26 (1 pl. to follow). Avy, J. E.—Microscopical Technology. On the exhibition (sic) of Canada Balsam. 5 [Directions for mounting sections of tissues in Canada balsam. ] Sci.-Gossip, 1884, pp. 5-8. Apy’s (J. E.) New Morphological Institution [for the production of micrographical preparations, and especially of rock and mineral sections]. Sci.-Gossip, 1883, pp. 276-7; 1884, p. 18. See also Nature, X XIX. (1884) p. 283. Ami, H. M.—Use of the Microscope in determining Fossils, with especial reference to the Monticuliporide. Science, III. (1884) pp. 25-6. AyLwarp’s (H. P.) Pond-life Apparatus. [Vol. IIT. (1883) p. 911.] Sci.-Gossip, 1883, p. 276. Barre, P.—Sur un procédé de préparation synoptique d’objets pulvérulents. Diatomées des guanos, terres fossiles, &e. (On a process of synoptic prepa- ration of pulverulent objects. Diatoms from guano, fossil earths, &.) [Post.] Bull. Soc. Belg. Micr., X. (1883) pp. 16-8 (1 pl.). BELFIELD, W. T.—The Microscope in the detection of Lard Adulteration. Proc, Amer, Soc. Micr., 6th Ann. Meeting, pp. 97-103 (1 pl.). Bennett, C. H.—Mounting Entomological Slides. [Treat the object for a week or a month, as the case may require, with liq. potassee until thoroughly bleached ; then, without removing the contents of the cavities, or in any way subjecting to the slightest pressure, mount in glycerine in a cell of ample depth so as to allow the object to retain its natural form and position. ] The Microscope, III. (1883) p. 220. Braman, B.—Microscopic Evidence of the Antiquity of Articles of Stone. Amer. Mon. Micr. Journ., VY. (1884) pp. 14-5. ZOOLOGY AND BOTANY, MICROSCOPY, E'rC. 155 Brooks’ (H.) Sets of sections of Woods for instruction in schools. [“ The sections are about 2 x 4 in., and are neatly mounted between plates of mica. Three sections (one cross and two longitudinal) are given for each kind of wood, and these are thin enough to make their study with the naked eye or with a low power very easy and instructive.” ] Amer. Natural., XVII. (4883) p. 1285. Burri., T. J.—Preparing and mounting Bacteria. Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 79-85. 55 is To stain Bacillus tuberculosis. [‘‘ Many ways have been tried to leave the alcohol out and yet obtain a stain as good as that of the published formulas. The following seems to be the thing sought:—Glycerine, 20 parts; fuchsin, 3 parts; anilin oil, 2 parts; carbolic acid, 2 parts.”—Also directions for use.] The Microscope, LV. (1884) pp. 6-8. CarPENnTER, W. B.—Remarks on Microscopical Observation. Syllabus of Carlisle Microscopical Society, 1884. Micr. News, IV. (1884) pp. 23-4. Cuapwick, H. C.—On some experiments made with a view of killing Hydroid Zoophytes and Polyzoa with the tentacles extended. [Supra, p. 151.] Micr. News, III. (1883) pp. 333-4. Cuester, A. H.—A new method of Dry Mounting. {Vol. III. (1883) p. 737.] Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 143-5 (1 fig.). Curyney, J.—The Microscopic Study of Fibres. [The Microscope in the dye-room—The marks of perfect dyeing—Marks of imperfect dyeing—The location of defects. ] Micr. News, IV. (1884) pp. 7-9, from Textile Record of America. Coz, A. C.—Popular Microscopical Studies. =. No. I1I. The Scalp. Vertical Section of Human Scalp. Double-stained. Plate 3 x 25. pp. 11-14. No. IV. The Ovary of a Poppy. Transverse section of Ovary of Papaver rheas (unfertilized). Plate 4 x 50. pp. 15-20. No. V. A Grain of Wheat. pp. 21-4. Plate 5. Long. sec. of Embryo at base of wheat-grain. Stained carmine. x 50. . » ._ The Methods of Microscopical Research. Part V. The Preparation of Animal Tissues (continued). pp. XXv.—xxxii. (2 figs.). ‘[Silver nitrate—Chloride of gold—Injection of Blood-vessels (Injecting Apparatus, Fearnley’s Constant Pressure Apparatus). ] Part VI. pp. xxxiii—xl. How to preserve Botanical specimens. On Animal and Vegetable Section-cutting. Rutherford’s, Williams’, Fearnley’s and Cathcart’s Microtomes. Gum and syrup preserving fluid. To cut tissues soaked in gum and syrup medium. Cutting by imbedding. nA Studies in Microscopical Science. Vol. II. No. 7. Section 1. No, 4. Epithelium. pp. 13-16. Plate 4, x 409. No. 8. Section 2. No.4. Chap. II. The Cell asan Individual. pp. 13-16. Plate 3 (Micrasterias denticulata x 200). No. 9. Sec.1. No.5. Cartilage. pp. 17-19. Plate 5. T. S. Hyaline Cartilage. Human Trachea x 250. No. 10. Section 2. No. 5. Chap. III. The Morphology of Tissues. pp. 17-20. (Plate to follow.) DowvEsweELL, G. F.—Note on a minute point in the structure of the Spermatozoon of the Newt. [Contains directions for preparing the spermatozoa, supra, p. 150.] Quart. Journ. Micr, Sci., XXIII. (1883) pp. 336-9 (1 fig.). Francorte, P.—Description des différentes méthodes employées pour ranger les coupes [et les Diatomées] en série sur le porte-objet. (Description of the differ- ent methods adopted for mounting sections [and diatoms] in series on the slide.) [Description of Mayer’s, Giesbrecht’s, Schallibaum’s, and Threlfall’s methods; also the application of the second and third to diatoms, supra, . 153.] e Bull. Soc. Belj. Micr., X. (1883) pp. 48-8, 63-6. 156 SUMMARY OF CURRENT RESEARCHES RELATING TO Francottr, P.—Microtomes et méthodes d’inclusion, I. (Microtomes and methods of imbedding.) [Describes Thoma’s Microtome and various methods already published. ] Bull. Soc. Belg. Micr., X. (1884) pp. 55-63 (1 fig. and 1 pl.). FrremMan, H. E.—Cutting Glass-circles. [Perforated wooden slips and writing diamond with turned point, the thin glass to rest on plate-glass ; very little pressure on diamond; it is better to leave the circles a day or two before breaking them out of the glass. ] Journ. of Microscopy, 111. (1884) p. 47. G., W. B.—Cement for objects mounted in spirits of wine. {Same as ante, Vol. III. (1883) p. 618. The cement a “secret.”] Midl. Natural,, Vi. (1883) p. 282. Gace, S. H.—Cataloguing, labeling, and storing Microscopical preparations. {Vol. III. (1883) p. 924.] Proc, Amer. Svc. Micr., 6th Ann. Meeting, 1883, pp. 169-74 (2 figs.). Discussion, pp. 236-8. a », and Surry, T.—Serial Microscopic Sections. [Post.] Medical Student (N.Y.) I. (1883) pp. 14-6. Giuuratt, H.—Some remarks on the action of Tannin on Infusoria. [ Vol. III. (1883) p. 861.] Proc. Linn. Soc. N. S. Wales, VIII. (1883) pp. 383-6. Grant, F.—Microscopic Mounting. IV. Section Cutting, Staining, &e. Es a 2. Section Cutting. 3. Staining. 4. Various practical etails. Engl. Mech., XX XVIII. (1883) pp. 285-6. V. The Use of Reagents. [1. The use of Reagents in general. 2. Glycerine and Syrup. 3. Acids and Alkalis. ] Engl. Mech., XX XVIII. (1883) pp. 365-7. VI. Chloroform.—Vegetable Objects. [1. Chloroform or Benzol, for thinning Canada balsam. 2. Non-fructifying organs of higher plants. 3. Ways in which vegetable sections should be cut. 4. Bleaching. 5. Staining. | Engl, Mech., XX XVIII. (1884) pp. 386-8. VII. Staining. [1. Staining in general.—Transient stains. 2. Metallic impregnations.— Diffuse, bioplasmic, and special tissue stains. 3. Hematoxylin and Carmine. 4. Indigo Carmine, Aniline, and Phthalein stains. 5. Double staining. | Engl. Mech., XX XVIII. (1884) pp. 449-50. Grirritu, E. H.—Practical Helps. [Ringing slides—Photograph slides—Mounts without covers—Arranging Diatoms, post. ] The Microscope, 111. (1883) pp. 204-6. H., H.—Microseopic Mounting. : Engl. Mech., XX XVIII. (1883) p. 266. Haacke, W.—Ueber das Montiren von Alcoholpraparaten. (On the mounting of alcohol preparations.) {For microscopic objects for Museums.] Zool. Anzcig. VI. (1883) pp. 694-5, Hamuin, F. M.—The microscopical examination of seminal stains on cloth. [Describes a new process, as “ Koblanck’s method, with its soakings and manipulations, tends to destroy so many of the spermatozoa as to lessen greatly the certainty of finding them.’’] Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 21-5. Discussion, pp. 220-5. Se ae LBs The preparation and mounting of Foraminifera, with de- scription of a new slide for opaque objects. [/Post.] Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 65-8. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 157 Hircucock, R.—Preservation of Museum specimens. [ Description of the Naples Zoological Station specimens at the Fisheries Exhibition. The living creatures are plunged into a solution of iodine or a strong solution of corrosive sublimate and transferred to dilute spirit, in which they are permanently preserved. | Amer, Mon. Micr. Journ., TV. (1883) pp. 217-8. s », _Exorbitant prices of mounted specimens of microscopic objects in America. Amer. Mon. Micr, Journ., LV. (1883) p. 218. 6 », Glycerine in Mounting. Amer. Mon, Micr, Journ., V. (1884) pp. 15-6. 0 » See Vorce, C. M. Jacoss, F'. O.—How to make a section of Tooth with pulp. The Microscope, TY. (1884) pp. 8-9. Kexuicott, D. S.—Notes on Protozoa. No. 2. [Agrees with the opinion of H. Gilliatt, III. (1883) p. 861, that the needle- like bodies seen when Paramecium is treated with tannin and glycerine are not cilia but trichocysts. ] Bull. Buffalo Naturalists’ Field Club, I. (1883) pp. 109-17. Kinestey, J. S.—Rapid Microscopic Mounting. [Describes Giesbrecht’s and Caldwell’s methods of series preparations. ] Science Record, II. (1883) pp. 1-2. x » Glycerine Mounting. (“One great difficulty in its use is in fastening the cover-glass firmly. Various modes of procedure have been described, possibly the best the writer has seen in print being that which employs paraffin. A still better method is to use a very small amount of glycerine, so little in fact that when the cover is applied the margin of the glycerine does not reach the edge of the glass. Then with a fiae brush, balsam or dammar dis- solved in benzol is allowed to run in under the edge of the cover- glass, and after becoming hard the superfluous balsam is cleaned off and the slide finished in any desired manner.” | Science Record, Il. (1883) p. 17. Konixe, F.—Die zweckmissigste Wasser-regeneration der Aquarien mit micro- scopischen Sachen. (The most effective mode of regenerating the water of s. Aquaria having microscopical objects.) [Post.] Zool. Anzeig., VI. (1883) pp. 638-9. Low-Sergeant, W. [Low-Sarjeant p, cxxxi—Low-Sargeant wrapper ].—New process for Preserving Plants. [Post.] Proc. and Trans. Croydon Micr, and Nat. Hist. Club, 1882-1883, pp. cii.—iii. Mager, L.—Technica Protistologica, Cloruro di Palladio. (Protistological Technics. Chloride of Palladium.) Bollett. Scientif., V. (1883) pp. 48-51. Mayer, P.—Einfache Methode zum Aufkleben mikroskopischer Schnitte. (Simple method of fixing microscopical sections.) [ Post. MT, Zool. Stat. Neapel, 1V. (1883) pp. 521-2. McCauia, A.—President’s Address to the 6th Annual Meeting of the American Society of Microscopists. The Verification of Microscopic Observation. [Vol. III. (1883) p. 766.] Proc. Amer, Soc, Micr., 6th Ann. Meeting, pp. 1-19. Morenouse, G. W.—A new Mounting Fluid. [Post.] Amer, Mon. Mier. Journ., TV. (1883) pp. 234-5. Mutter, C. J.—The discrimination of Species of Wood by a microscopical exami- nation of sections of branches. Trans. Eastbourne Nat. Hist. Soc., I. (1883) pp. 4-12. ParieTTI, E.—Ricerche relative alla preparazione e conservazione di Bacteri e d’Infusori. (Researches on the preparation and preservation of Bacteria and Infusoria.) Bollett, Scientif., V. (1883) pp. 95-6. 158 SUMMARY OF CURRENT RESEARCHES RELATING TO Peticouas’ (C. L.) New Slides of Diatoms. [Slide No. 1, Stawroneis acuta.—Microscopists are familiar with the beautiful effects of dark-field illumination upon certain diatoms. Some peculiarities of structure are shown by this method more clearly than by transmitted light. A recent gathering of St. acuta (Pleurostaurum acutum Grunow) has given me a sensation, although I have practised this method of illumination for years. With a 1/2 inch objective and a strong artificial light on dark field, this diatom seems literally to blaze, and surpasses in splendour the finest polariscope objects in my cabinet. With the light thrown across the short diameter, there is a strong resemblance to a section of ostrich tendon, only some peculiarity of striation seems to impart motion to the light, and the diatom seems on fire ; across the long diameter the colour is changed to a brilliant sapphire. ] Amer. Mon. Micr. Journ., IV. (1883) p. 234. Pitispury, J. HA new Microscope Slide Cabinet. [ Post. ] Science Record, II. (1883) pp. 25-6 (2 figs.). Queen, J. W. & Co.—Improved Slide Box. [Covered with cloth instead of paper ; inside of lid with numbered lines for indexing. | Micr. Bulletin, I. (1883) p. 7 (1 fig.). R., D.—Classification and Labelling of Mitroscopical Objects. [Suggestion that locality should be added to I. C. Thompson’s labels, Vol. III. (1883) p. 926.] Sci.-Gossip, 1883, p. 276. Rauru, T. S.—Thymol as a Polariscopie Object. [A most splendid polariscopic object. If a very small piece, about the size of a mustard-seed (or perhaps two) is placed at the edge of a cover-glass on a slide (not under), and then made to melt, it will run under it ina very fine film and crystallize on cooling. But before this take place, it should be placed on the stage, with the polarizing apparatus ready, so as to watch the process of crystallization. The effects far exceed that of most polariscopie objects. The same specimen carefully remelted can be used over and over again. | 3 Journ. of Microscopy, III. (1884) pp. 31-2. RavTAaBowL, J.—Les Diatomées. Récolte et préparation. I. Récolte des Diatomées. (The Diatomacez. Collection and preparation. I. Collection of the Dia- tomacese.) (In part.) Journ. de Microgr., VII. (1883) pp. 644-6 (1 pl.). Retnoip, A. W., and A. W. Ritckur.—Liquid Films and Molecular Magnitudes. [ Post. | Proc. Roy. Soc., XX XY. (1883) pp. 149-51. Renson, C.—Nouveau procédé de recherche des Trichines dans les Viandes. (New method of research for Trichine in meat.) [ Post. ] Bull. Soc. Belg. Micr., X. (1883) pp. 24-25. Rorsrock, J. T.—Some microscopic distinctions between good and bad Timber of the same species. Amer. Phil. Soc., Feb. 1883. RorHWELL’s (W. G.) Educational Slides. WMicr. News, U1. (1883) p. 340. Royston-Pigort, G. W.—Note on the structure of the Scales of Butterflies. Trans. Eastbourne Nat. Hist. Soc., I. (1883) pp. 41-5. Ricker, A. W.—See A. W. Reinold. Scuarrrer, HE. M.—'he Microscopical Study of the Crystallization of Allotropic Sulphur. [Contains directions for preparing. ] Amer. Mon. Micr. Journ., V. (1884) pp. 1-3. ScHNETZLER.—Notiz iiber Tanninreaction bei Siisswasseralgen. (Note on the reaction of tannin in the fresh-water Algee.) _[Post.] Bot. Centralbl., XVI. (1883) pp. 157--8. Scott, W. B.—Imbedding in Egg-mass. [ Ruge’s ae of Calberla’s method. Cf. Vol. III. (1883), pp. 303-4. Science Record, III. (1883) pp. 41-2. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 159 Siack, H. J.—Pleasant Hours with the Microscope. [Muscular System of Insects. | Knowledge, TV. (1883) pp. 316-7 (2 figs.), 383-4. 5 B [Trichine. ] 9 VY. (1884), pp. 20-1 (2 figs.). 3 és [ Examination of atmospheric dust. | on oe pp. 51-2 © figs.). STANLEY’s Stained Sections for use of students. [In tubes ready for mounting and previous examination, so that students can try the effect of reagents upon them before putting them up as permanent objects. A circular accompanies, detailing the method of mounting and what to observe in the finished slides. ] Mier. News, III. (1883) p. 340. TarANEK, K. J.—Monographie der Nebeliden Bohmen’s. {Contains a note on preparing Fresh-water Rhizopoda. Post. ] Abh. K. Bohm. Gesell. Wiss., XI. (1882) Art. No. 8, iv. and 56 pp. (5 pls.). Taytor, T.—Freezing Microtome. Proc. Amer. Assoc. Adv. Sci., 1881, pp. 119-21. THoma, R.—Microtome 4 glissement et méthodes d’enrobage. (Sliding Micro- tome and methods of imbedding.) [Same as ante, Vol. III. (1883) p. 298, and post.] Journ. de Microgr., VII. (1883) pp. 576-83 (7 figs.), pp. 639-44 (1 fig.) Tuompson, I. C.— Microscope Labels. [Claim of priority over Mr. Quinn for the labels described Vol. IIT. (1883) p. 926.] Micr, News, III. (1883) pp. 334-6. Tuomson, W.—The size of Atoms. [Post.] Proc. Roy. Instit., X. (1883) pp. 185-213 (11 figs.). Vorce, C. M.—The microscopical discrimination of Blood. [Six propositions “generally and with rare exceptions true,” setting forth the author’s “views of micrometry in general in relation to minute objects, including blood.”] Also comments by R. Hitchcock. Amer. Mon. Micr. Journ., TV. (1883) pp. 223-5, 238-9 ; V. (1884) pp. 17-8. i 5 Expanding the Blow-fly’s Tongue. [ Post.] Amer. Mon. Micr. Journ., V. (1884) p. 12. W., D. S.—Washing and mounting objects containing a considerable quantity of air. [Post.] Amer. Mon. Micr. Journ., V. (1884) p. 18. Warp, E.—Mounts and Mounting. [Abstract of the author’s ‘ Microscopical Mounts and Mounting,’ and ‘ Micro-crystallization.’ ] Amer. Mon. Mier. Journ., TV. (1883) pp. 149-56 (in part). West, T.—“ Polariscope objects, with few exceptions, are merely pretty things, well enough calculated, in moderation, to relieve the solid bill of fare at a soirée or conyersazione, but nothing whatever is to be learnt from them save that by certain arrangements of apparatus belonging to our Microscopes, some things become decked in gay colours; that is literally all.” [This statement will, we think, be generally recognized as very much too sweeping !—Ep. J.R.M.S. | Journ. of Microscopy, III. (1884) p. 47. Wurman, C. O.—Recent improvements in Section-cutting. [Contains abstracts of Andres, Giesbrecht, and Mayer’s section-smoother, III. (1883) p. 916—The registering micrometer-screw, IIL. (1883) p. 914 and supra, p. 153—The new object-holder, III. (1883) p. 915—An improvement in the carriers, III. (1883) p. 916—Type-metal boxes for imbedding, ILI. (1883) p. 913.] Amer. Natural., XVII. (1883) pp. 1311-16 (8 figs.). Wuitman, C. O.—Methods of preventing the rolling of microtomic sections. [Transverse knives, post. Schulze’s section-smoother (1 fig.) III. (4883) p. 400. ] Amer. Natural.. XVIII. (1884) pp. 106-8 (1 fig.). 160 SUMMARY OF CURRENT RESEARCHES, ETC. Woopwarp, A. L.—Unpressed mounting of the Tongue of the Blow-fly. [‘‘ While it is an easy matter to catch and decapitate your blow-fly, unfor- tunately he will not always protrude his tongue properly during the operation, and my experience is that the tongue remains for ever after fixed in the position that it happens to be in when life in the fly becomes extinet. To remedy this, I tried the plan of immersing the living insect in alcohol, and with perfectly satisfactory results. At the moment of death the tongue is forcibly protruded to its entire length. Even the short proboscis of the house-fly is satisfactorily displayed. I tried carbolic acid in the same way, but the results were not nearly so good, and, besides, alcohol is a much nicer fluid to handle.”] Amer. Mon. Micr. Journ., LV. (1883) p. 239. Waicut, L.—Microscopical Mounting. [impossibility of procuring insect preparations “mounted in a really jirst- class manner,” &¢. | Engl. Uech., XX XVIII. (1883) pp. 343-4 (2 figs.). ( 161 ) PROCEEDINGS OF THE SOCIETY. Meertine or 127TH Decemper, 1883, at Kine’s Cottece, StRanp, W.C., Jamus GuaisHER, Ese., F.R.S., Vicz-PREsIDENT, IN THE CHAIR. The Minutes of the meeting of 14th November last were read and confirmed, and were signed by the Chairman. The List of Donations (exclusive of exchanges and reprints) re- ceived since the last meeting, was submitted, and the thanks of the Society given to the donors. From Balbiani, G.—Lecons sur les Sporozoaires. viii. and 184 pp. (51 figs. and 5 pls.). 8vo, Paris, 1883 Be etal cg tates oy Leas The Author. Ferguson, J.—The Microscope, its Revelations and Applications in Science and Art. viii. and 160 pp. S8vo, Edinburgh, 1858 .. Mr. Crisp. The Chairman said it was his painful duty to announce that since their last meeting, the death had occurred of one of their number, who during almost the whole of his life had been held in the highest esteem and respect by all microscopists. He referred to Mr. Hugh Powell, of the firm of Powell and Lealand. It was truly a ripe old age to which he had attained, but nevertheless it was always painful when at length the time of parting came, and both as a Society and as individuals, he was sure they must deeply regret the removal of one whom they had always held in such respect. It was by an unfor- tunate coincidence that it fell to his lot to announce to the same meeting the death of Mr. Powell’s most distinguished rival in America, Mr. R. B. Tolles, of Boston, who had also done so much for the improvement of objectives. Peace be to both of them, with the kindliest feelings of sympathy towards their respective families, of every Fellow of the Society. Mr. Crisp exhibited (1) Mr. H. P. Aylward’s Microscope, having a swinging tail-piece rotating completely round the stage, so that the mirror and substage could be set in any required azimuth (p. 110); (2) a Microscope by Mr. A. McLaren, rotating upon the horse-shoe foot, so as to secure greater stability for the instrument when the body was inclined at any considerable angle (p. 111); (3) a Microscope by Herr F. W. Schieck (p. 112), with a number of objects inserted in the circumference of a revolving drum, so that each could be passed in turn beneath the objective. A translation of the inventor’s de- scription of the instrument and its advantages was read to the Ser. 2.—Vou. IV. M 162 PROCEEDINGS OF THE SOCIETY. meeting, and his claim to absolute originality shown to be erroneous by the exhibition of Harris’s Microscope (p. 115), obviously of con- siderable age, in which the same idea had been carried out. Mr. W. H. Walmsley’s photo-micrographs were exhibited, two of which in particular (of Moller’s diatoms) were characterized by the Chairman as very excellent examples of photo-micrography. Mr. W. M. Bale’s note on Mounting in Glycerine was read. Dr. J. H. L. Flogel’s paper on “ Researches on the Structure of Cell- walls of Diatoms ” was brought before the meeting by Mr. J. Mayall, jun., who, in his preliminary remarks, said that it would be remembered that some time ago they had heard reports that some one abroad was making sections of diatoms, and he was requested by Mr. Crisp to institute inquiries with the view of bringing the method before the Society. He subsequently found that this work was being done by Dr. Flégel of Holstein, who, there appeared no reason to doubt, was not only a skilled and competent observer, but that he possessed every kind of appliance for making careful observations. Having ascertained this, the next thing was to obtain specimens of actual sections of diatoms, without which it was of course not possible to form any satisfactory judgment on the matter. He was fortunate in persuading Dr. Schroder, now resident in London, to write to Dr. Flégel upon the subject, and in the result they had received a very elaborate paper accompanied by a dozen slides and a number of photographs and drawings in illustration. A careful examination of the slides showed that Dr. Flégel was thoroughly familiar with the finest processes of mounting, and with all that had been done by Moller. One of the slides was exhibited in the room under a 1/25 in. objective by Mr. Powell. It was a section of Triceratium favus, and the excellence of the specimen gave rise to the impression that something even more difficult than this could be accomplished. Amongst the other specimens sent, were some very clean cut sections giving an exceptionally clear image. It was stated by Dr. Flégel that as many as 174 transverse sections had been made of one diatom, all of which could be plainly identified as belonging to the same diatom. Mr. Mayall said that he could not pledge himself as to the correctness or otherwise of the theory set up by the author of the paper, as the subject was not one which he had made his own, although he had taken some pains to translate the paper for publication in the Journal of the Society. Mr. Mayall then read an abstract of the paper to the meeting, and the subject was discussed by Mr. Curties, Mr. Crisp, and other Fellows. The Chairman in proposing a vote of thanks to Dr Flégel for his paper, said that he was sure the Society would feel doubly indebted to Mr. Mayall for the exertions which he had made to procure the paper, and also for trouble he had taken in the matter of its translation. PROCEEDINGS OF THE SOCIETY. 163 The following Instruments, Objects, &c., were exhibited :— Mr. Crisp :— (1) Aylward’s Rotating and Swinging Tail-piece Microscope. (2) McLaren’s Microscope with Rotating Foot. (8) Schieck’s Revolver School and Drawing-room Microscope. (4) Harris’s Revolver Microscope. Dr. J. H. Flégel:—Sections of Diatoms illustrating his paper. Mr. J. Mayall, jun. :—Ditto. Mr. T. Powell :—Ditto. Mr. W. H. Walmsley :— Photo-micrographs. New Fellows :—The following were elected Ordinary Fellows :— Messrs. John Butterworth, W. T. Cleland, M.B., T. B. Rossiter, and Andrew F. Tait. CoNVERSAZIONE. The first Conversazione of the Session was held on the 8th November, 1883. The following objects, &c., were exhibited :— Mr. H. P. Aylward : Set of collecting apparatus. Mr. Chas. Baker : New Mineralogical Microscope by Zeiss. Portable Student’s Microscope by Leitz. Stewart’s Safety Stage. Test Diatoms in monobromide of naphthaline and phosphorus, by Maller. Mr. J. Badcock: Ophrydium Hichhornit and Fredericella sultana. Messrs. R. and J. Beck: Bacillus tuberculosis in liver of a bird, and Bacillus Anthracis in human liver. Mr. Thos. Bolton : Cordylophora lacustris. Mr. W. G. Cocks : Megalotrocha albo-flavicans. Mr. F. Crisp: Type-Plate of 400 Diatoms, with names photographed, by J. D. Moller. Mr. G. F. Dowdeswell : Spermatozoa of Water Newt (Triton cristatus). (1) Showing general structure, with the filament and membrane. x 200 diameters. Powell’s 4/10 in. (2) Showing minute barb on point of head of the same. x 8600 diameters. Powell’s 1/24 in. homogeneous immersion, N.A. 1°37. Mr. F. Enoch : Various species of minute Hymenoptera. Mr. F. Fitch ; Dissection of Phalangium opilio. 164 PROCEEDINGS OF THE SOCIETY. Mr. H. H. Freeman: Acarina from a hay-rick. Mr. J. W. Groves : Hydra fusca and Ameba of large size. Mr. A. de Souza Guimaraens: Hyphersthene, St. Paul’s Island; Porphyritic Melaphyre, Plauen, near Dresden. Stained blue? Mica Diorite, Freiburg; Mica Diorite, Wolsau, Fichtelgeb. ; Quartz Diabase, Gotha; Quartz Diorite, Bingen. The same rock ? Mr. H. Hailes : Abnormal forms of Foraminifera (Peneroplis). Mr. J. D. Hardy: Chromatoscope and transverse section of eyelash of Whale. Mr. J. E. Ingpen: Cyclosis in Australian Vallisneria. Mr. W. Joshua: Sea skimmings from the east coast of New Guinea, containing the following species :—Rhizosolenia styliformis, striata, alata, seti- gera, calcaris, Shrubsolii ; Cheetoceras peruvianus and Wighamu ; Ooscinodiscus nobilis, concinnus, radiatus; Lauderia annulata ; Meelleria caudata ; Eucampia zodiacus ; Palmeria Hardmaniana ; Melosira grandis, &e. Dr. Matthews : Sponge from the base of Stylaster. Mr. J. Mayall, jun. : Dr. Schréder’s Camera Lucida. BS 1/4 in. Eye-piece. si 1 in, do. McLaren’s new Fine Adjustment. Mr. A. D. Michael : Hoplophora magna. The muscles for raising the cephalothorax, showing the tendonous attachments; and a trachea of Dameus geniculatus, showing the spiral structure not before detected. Mr. E. M. Nelson: Human Spermatozoon, showing a division in the tail not before observed, with Powell and Lealand’s oil-immersion 1/12. Mr. F. A. Parsons: Cerataphis latanic, the Horned Aphis. Messrs. Powell and Lealand: Scale of Podura with 1/25 oil-immersion, N.A. 1°38. Mr. B. W. Priest : Section of Placospongia melobesioides, and Plumularia setacea, with tentacles expanded. Mr. S. O. Ridley : ‘Challenger’ Deep-sea Sponges. Messrs. Swift and Son: Small Petrological Microscope. Mr. G. Smith: Fossil Wood silicified in section; Dolerite, &e. PROCEEDINGS OF THE SOCIETY. 165 Mr. C. Stewart : Scale of Lizard (Cyclodus ?). Mr. J. H. Steward : Davis’s Central Aperture and Iris Diaphragm, and Prowse’s Ophthalmoscope. Mr. Amos Topping: Some Vegetable Preparations. Mr. J. G. Waller: Excavating Alge? in calcareous particles from the Gabbard and Galloper Sands, off east coast of Essex (decalcified). Mr. H. J. Waddington: Examples of Foliated Crystals, polarized Erythrite, Sulpho- carbolic acid (?), Kinate of quinine, and Magnesium platino- cyanide. Meetine of 97TH January, 1884, ar Kine’s Cottear, Stranp, W.C. Tur Present (P. Martin Dunoay, Esq., F.R.S.) 1n THe Caarr. The Minutes of the meeting of 12th December last were read and confirmed, and were signed by the Chairman. The List of Donations (exclusive of exchanges and reprints) received since the last meeting was submitted, and the thanks of the Society given to the donors. Harting, P.—Recherches micrométriques sur le développement From des Tissus et des Organes du Corps humain, précédées d’un examen critique des différentes méthodes micrométriques. viii. and 88 pp. 4to, Utrecht, 1845 .. Mr. Crisp. Heller, K. B.—Das dioptrische Mikroskop, dessen Einrichtung und Behandlung. vi. and 56 pp. (18 figs.). 8vo, Wien, 1856 Mr. Crisp. Magnin, A., and G. M. Sternberg.—Bacteria. xix. and 494 pp. (80 figs. and 12 pls.). 8vo, New York, 1884 .. .. .. Dr. Sternberg. Set of Collecting Apparatus... . eA wae se Mr. H. P. Aylward. Slide of Microthamnion vexator (Cooke) Si oa. od “Sod 00 MURS WG 18, War Mr. Crisp exhibited and described Mr. Bulloch’s new Objective Aitachment (p. 118), which he thought was more complicated than was at all necessary, and which on that account could not be considered an improvement on that of Mr. Nelson, or the Matthews-Watson form. - Mr. John Mayall, jun., exhibited and described (1) Mr. Parsons’ Current Slide (p. 121), and (2) Nelson’s Microscope Lamp, with the oil vessel in the original square form (p. 125), and also with the im- proved round vessel as suggested by himself. With the exception of the very elaborate and expensive lamp devised by Mr. Dallinger, he considered this to be the best lamp yet produced for microscopical purposes. Mr. Crisp pointed out that the device made use of in Mr. Parsons’ slide was adopted by M. Nachet, some years ago, for adjusting the depth of the cell in counting blood-corpuscles. 166 PROCEEDINGS OF THE SOCIETY. Mr. W. J. Sollas’s letter on the subject of cutting sections of diatoms was formally laid before the meeting. It had reference to the paper of Dr. Flégel, read at the December meeting, and was also intended to be read at that meeting, but did not come to hand until the meeting was over, when it was informally communicated to those present. The letter was as follows :— “ For some time past I have been engaged in cutting sections of diatoms. My plan is to scrape off a green slime from our river mud, consisting chiefly of Pleurosigma zigzag—a large species suitable for cutting. The slime, together with some mud, unavoidably gathered at the same time, is placed in a saucer and covered with a piece of muslin, which les in immediate contact with the mud, while a film of water lies above it. The saucer is now exposed to daylight, and the diatoms creep through the muslin, collecting in a consistent film on its upper surface. The muslin may now be lifted from the mud, it comes away clean bringing all the diatoms with it, but leaving the mud. The muslin with the diatom film is now immersed in the usual hardening and staining reagents. I have used a mixture of chromic and osmic acids and absolute alcohol for hardening ; borax-carmine, hematoxylin, and eosin for staining. When duly stained and hardened the diatom films may be removed from the muslin without difficulty, and cut, either by imbedding in pure paraffin (melting point 58°) and mounting in Canada balsam, or by freezing in gelatine jelly, which allows one to cut consistent sections which may be mounted direct in glycerine on a glass slide, without passing through water. By em- ploying these two processes, I have made out the internal structure of diatoms, and believe that I can detect fine protoplasmic threads pro- ceeding from the protoplasm that surrounds the nucleus and passing through apertures in the median keel. I am not yet, however, in a postion to demonstrate this with absolute certainty, but hope to do So soon.” Dr. Beale gave a resumé of his paper on “The Constituents of Sewage in the Mud of the Thames” (p. 1), illustrating his remarks by numerous drawings, and pointing out the important bearing of the matter upon the question of the health of the population of London in the probably near future. The President thought the Society would feel greatly indebted to Dr. Beale for bringing before it this very unpleasant subject in a truly scientific spirit. Of its great importance from a sanitary point of view there could be no manner of doubt. Mr. Bennett said he could confirm from his own experience the view expressed by Dr. Beale, that by no means all of the sewage of London was discharged into the Thames. As an instance in point, he might say that he had lived for some time in the north of London, and had recently discovered that there was no connection between the house and the main drain, but that the house drains merely led to a cesspool. He was told that this was the case with at least half the other houses in the road. He should be sorry to appear to throw the slightest doubt on any point touched upon by Dr. Beale, as of course, PROCEEDINGS OF THE SOCIETY. 167 when they appeared in print, many of the particulars would be more fully entered upon; but with regard to the spiral vessels of plants found in the mud, and the suggestion that they belonged to cabbage which had passed through the intestinal canal of man, he believed that it was a fact that they were without any work upon the anatomy of the spiral vessels which was at all conclusive upon the subject, or any information which would enable them to discriminate between the spiral vessels of different plants, or between those from different parts of the same plant. Before, therefore, it would be possible to accept the evidence as conclusive, they required some controlled experiments to prove that such things did not exist in water which was free from all suspicion of sewage. The cabbage, as was well known, belonged to an order of plants very common on the banks of the ‘Thames, watercress for example growing there in large quantities, besides which cabbage was an article extremely likely to be thrown overboard from vessels and barges, so that he should be very careful in coming to a conclusion that these spiral vessels necessarily had their origin in the sewage. Dr. Maddox said that some years ago he made a similar examina- tion of water and mud from a field which had been irrigated with sewage. He took some from the inlet, and the other from a place just below the inlet, and he had not the slightest difficulty in recog- nising specimens in Dr. Beale’s drawings as being of the same kind as those which he found on that occasion. Amongst other things, it was quite easy to identify muscular fibre, some of which was very imperfectly digested, also minute portions of broken shell, but the chief thing which struck him was the great excess of muscular fibre in proportion to the quantity of vegetable matter. There might have been portions of coal, but he did not remember recognizing its struc- ture so clearly as Dr. Beale had done, but it struck him as being a dangerous process to irrigate fields with this kind of refuse, and then to drink the water from streams into which such water drained. Dr Beale said he quite agreed with Mr. Bennett that it was impossible actually to identify the spiral vessels, but having regard to their identity with those obtained from cabbage, the chief point upon which he laid stress was the very great quantity of them found, in excess of all that could be well accounted for in any other way. Then again, it was well known that the number of vegetables growing upon the banks of the river went on decreasing, whilst the quantity of mud kept increasing. There was one point of interest in connec- tion with the subject which he ought to have mentioned, and that was the marked difference in the death rate of London since the present system of drainage was adopted. In 1870, when the system was first set to work, the rate of mortality was 24-4, and it had since that time decreased, until now it was only 21:4, so there was every encouragement for every one to do his best to get rid of the sewage, or to dilute it still further. Mr. Crisp referred to a paper by Mr. G. Acheson (Proc. Canad. Inst. i. (1883) pp. 413-26), with fourteen pages of description of organisms found in the tap water of Toronto. 168 PROCEEDINGS OF THE SOCIETY. Col, O’Hara’s communication on some peculiarities of form and in- dependent movement in blood-corpuscles, and a subsequent letter on the subject were read. Photo-micrographs in illustration were also exhibited. Dr. Maddox said that in Dr. Sternberg’s “‘ Photo-micrographs,” a blood-corpuscle from a yellow-fever patient was figured which he thought showed the same kind of appearance as that described. Col. O’Hara also further explained the results of his examination. Mr. Crisp read a letter from Dr. Van Heurck on the advantage he had found in mounting in styrax, and exhibited the slides which he had sent. Mr. J. P. Bisset’s “ List of Desmidiex, found in gatherings made in the neighbourhood of Lake Windermere during 1883,” was taken as read. Mr. W. B. Turner’s communication on Microthamnion veaator, anew species of fresh-water alge, was read, and a specimen exhibited. Mr. Crisp read a list of Fellows who had been nominated for election at the February Meeting as Officers and Council for the ensuing year. Mr. P. J. Butlerand Mr. R. Kemp were duly elected Auditors of the Treasurer’s accounts. The following Instruments, Objects, &c., were exhibited :— Dr. Beale :—Slides illustrating his paper. Mr. Crisp :—Bulloch’s Objective Attachment. Mr. J. Mayall, jun. :—(1) Parsons’ Current Slide; (2) Nelson’s Microscope Lamps. Col. O'Hara :—Photo-micrographs of Blood-corpuscles. Mr. W. B. Turner :—New Fresh-water Alga. Dr. Van Heurck :—Diatoms mounted in styrax. a ‘The J ournal is issued on the ‘second Wednesday of February; April, June, August, October, and December; ee ae ws 220 Sucking Organs of Flies’ .. ..» Uinta baat at aoe ee mei wos Visceral Nervous System of Periplaneta orientalis .. SPE ater ea ene eat Geo) OR Pulsating Organs in the Legs of ss a nth cami Zibe Os Vet aqtlne ee? erat tale geome Vitelline Nucleus of Aranewna, wie OMe witty Wari ad oie Anata Wy NU GN om OAC aS ened eae Restoration of Limbs in Tarantula .. Se ee ae eine N Morphology of Plumicolous Sarcoptide .. 6.0 ee ne ee ne BOB Sexual Characters of Limulus .. Se ohaeel Nea Teoe DOG Evidence.of a Protozoea Staye in Crab Development See ute clues Ap ames ONS ‘Gastric Mill of Decapods .. 3 een Mane sare Naat ee) J7 Spermatogenesis in edriophthalmate Crustacea, 3 ie NO oR Structure and Division of Ctenadrilus melee ray fer Cie aa ede OO Manyunkia speotosa 6.0 0 see ee ee a BT ona” - Somany OF Current Rnsnnonné, Ke ontinwed Parasitic Nematode of the Common Onion SA GRREeS Se Maen 77 New Myzostomata Roce PEE SIAC WONT RARE we ELI Bucephalus and Gasterostomum. Se Lae os op cua ea oh due. ied Development of Dendrocelum lacteum, .- ++ 24 0 ee - Rotatoria of Giessen... ». Pere se ee mpemn Nas Rotifer within an ‘Acanthocystis New Alcyonarians, Gorgonids, ang, Pennatulids of the Norwegian Seas Origin of Coral Reefs.. ... és Porpitide and Velellide .. SAMI Dele rupan Ny ne Scene Physiology of Gemmules of Sponqilidee ESA acrylate eerie o> ee European Fresh-water Sponges .. Sa Spa fide ates New Genus ay Bppaget Rate emer ae) SER Biitschli s‘ Protozoa’. Psy Wat ENG ety anlar a wattle New Infusoria why Reproduciton in Amphileptus fasciola. Orders of the Radiolaria .. 2. 6s 98 ae Bohemian Nebelidz 2. 1. 2. ewe oe Borany. Living and Dead Protoplasm- lee ageg eit Reon ge ee Aldehydic Nature of Protoplasm .. +s 10 29 048 28 -Embryo-sac and Endosperm of Lanne DC Ween Gahan es kee Ge Constitution of Albumin’... .« Set Melee siagie teen sal hes Corpuscula of Gymnosperms wes th oss Comparative Structure of the Aerial and Subterrancous _ Dicotyledons 7 Junction of Root and Stem am Dicotyledons and Menocotyledons. Suberin of the Cork-oak .. Be Influence of Pressure on the Growth ‘and ‘Structure of Bark. eae Relation of Transpiration to Internal: Processes of Growth. +» Easily, Oxidizable Constituents of Planis.. +. +2 «= ss Action of Light on the Elimination of Oxygen s ae Red Pigment of Flowering Plants .. sanicee Coloured Roots.and other coloured Bar of Plants eS ome Oospores of the Grape Mold cto fob ee hae Siya Pleospora gummipara PP ira un oe an Rc cual Pater eLeterg Schizomycetes 4. a» ne ae ne we aes . Fecal Bacteria ... os Influence of Oxygen aot high pressure on Bacillus anthracis as - Bacteria in the Human Amnion ~~ 1.4, «2 os 00 / oe 08 Bacillus of “ Rouget” .« Niailine LSet eaten oe Living Bacillt in She Cells of Valtisnoria ae o Simulation of the Tubercular Bacillus by Orystaltine F ani ae Cultivation of Bacteria... - fede o Reduction of Nitrates by Ferments .. See ane ’ Rabenhorst’s Cryptogamic Flora of Germany (Alger) shee tag aie Distribution of Seaweeds». Sal Sea reani Bepi tes Cystoseirz of the Gulf of Naples Seen arial eed Simentt ar ees Seung = See uN Suni a eh GaN r ree aes Starch in the Root... AS Proteids as Reserve-food Materials . SPAS uous huey pa Leucoplastids ... PO AETES At Saoas ty heey 2 ON te Cleistogamous Flowers. Cultivation of Plants in Decomposing Solutions of Organic Matter Disease of the Weymouth Pine... .. Pre Bere Flora of Spitzbergen -« Sepa e cea’ ae corer i Ae Fructification of Fossil Hove 2 oes ies -Prothallium of Struthiopteris germanica +. ee ne ww Mucilage-organs of Marchantiacer .. s+ ++ os 25 oe ' Characee of the Argentine Republic... ++ 06 se 08 American Species of Tolypella .. Pe Rabenhorst’s Cripepae Flora ous Germany Fungi -. sel tees Hysterophymes .. +» ac ba Scakrr eee Graphiola.. .. fe age ee TS a bie enh yack Mier emi en Pourvidié of the Vine WSL pir pel eee Stem ve m of oo Sommany OF Conrenr -Rusuarouus, &e. (an 5 confined: Pithophora eo ; eo. ae es co oo oo ma J ae Resting-spores of AGRO et Mes ihwa ohare wai eel Hybridism in the Conjugate .. 1. | New Genera of Chroococcacez and Palmellace : a. Chroolepus umbrinum.. Constant Production of Oxygen by the Action of Suntight on pluvialis~ .. Rep iim ey hee win Chromatophores of Marine Diatoms.. 1... Division of Synedra Ulna.. se 5 se we ua te Arctic Diatoms ... we evaah eat ks aol’ Ge Pelagic Diatoms of the Baltic .. ey ey ces Siena? of Lake Bracciano +. +. ou, we as Microscory. Ahrens’ 8 Ereeting Microscope (Fig. BB) een ove Bulloch’s Improved “ Biological.” ‘Microscope. ee Cox's Microscope with Concentric Movements oe) Geneva Company's Microscope (Figs. 30 and oe “ Giant Electric Microscope” ).. Bp ehlia Tolles’s Student’s Microscope (Fig. 32) Beenie - Winter's, Harris's or Rubergall’s Revolver Microscopes a Geneva Co.’s Nose-piece Adapters (Fig. 33)... ‘Lornebohin’s Universal Stage Indicator .. .. +. Stokes's Fish-trough (Figs.39 and 36)... 2. © 2. “Nelson-Mayall Lamp (Fig. 37) 0... as) oe ae = Standard Micrometer Scale... BS hai - Microscopie Test- Objects (Figs. 3g and 30), wate Aperture and Resolution (Figs. 40 and AV) ices ~The Future of the Microscope .. 1. 4. os Webb’s ‘ Optics without Mathematics’ oe -. . Lentmayer's Nose-piece Hig. 34). ee wee ee ae ae ee Preparing and Mounting Sections of Teeth and Bone ae me c Expanding the Blow-jly’s Tongue .. ee ee oe ee ee ee ee ee s eo ee eo ‘Protococcus Sa bes eo ee OL oe oe eo oo” we ‘ee ee eo o ee ee gia jee ee eo» ee se oe e ee oe oe oe 7e ee Perchloride of Iron as a reagent for Preserving Delicate Marine Animals Action of Tannin on Infusoria.. ©... a - Preparing Fresh-water Rhizopoda igh doen datanree Arranging Diatoms 2. es ne ne ae ae \ Mounting Diatoms in Series — .. Synoptical Preparation of Palecrulent Oe ‘irate a Guano, Fossil ue Earths, &e.) (Fig. 42) 3. Pte ee Logwood Staining .. Pana ier we, tina tee) Siaining with Hematoxylon Hoe PSipalll’, weceee eh del Dry Injection Masses... .. ae ade a Schering’s Celloidin for Tmbedding ae oe ees Gage’s Imbedding-mass Cup (Big. 438). te oe Gage and Smith's Section-flaitener (Fig. 44). _ Francotie's Section-flattener (Fig. 49) Employment of the Freezing Method in Histology «. ae Improved Method of Using the Freezing Microtome Mayer's Method of Fixing Sections 1. 22. sus Gum and Syrup Preserving Fluid. «+ Cutting Tissues soaked in Gum and Syrup Medium Gum Styraz as.a Medium for Mounting Diatoms.. Mounting Medium of High Refractive Index... “.. Kingsley’s Cabinet for Slides (Fig. 46) oer gare Pillsbury’s Slide Cabinet (Fig. 47) +o. Examining the Heads of Insects, Spiders, &e., , alive a Examining Meat for Trichine .. ‘<< 2. Bolton's Living Organisms... .. — oe Cole’s Studies in Microscopical Beience .. .. ae “Proceepines or THE SOCIETY =. ke eo eo eo | ee > . « © e ee ee ) ee eo Lee eo : ee eo . 20 Pea e ale ° e oe . oe ° ° ae oe e oe eo eo we oo ee ee oe ao ee oe » ep Oi ae 2. oo oe oo oo) oe we ae ee e> 0 6 ee ee ae ee e * eo e eo ee 26 ae Un) "ROYAL MICROSCOPICAL SOCIETY. “COU N CIL. ELECTED 13th FEBRUARY, 1884. - PRESIDENT. By. W. H. Daturnerr, FR. 8. VICE-PRESIDENTS. - Jonn Anrnony, Esq., M.D., F.B.C.P.L. Pror. P. Marri Dunoay, MB. FBS. James GuaisHER, Hsq., FR. S., R, R.A.S. CHARLES STEWART, Esq,, » MBCS., a LS. TREASURER, Lions S. Bears, Esq., M.B., ee ERS. SECRETARIES. ure Crisp, Esq., LL.B., B.A. V.P. & ‘Treas. LS. -Pror. E, Jerrszy Bret, M.A., ¥ ZL. 8. "Twelve other MEMBERS of COUNCIL, Aurrep Wioiiam Bennett, Esq., M.A., B.Sc., F.LS, - Roserr BrarrHwarre, Esq., M.D., M. R, C. 8, FL. B. G. F. Dowpzswetn, Hsq., M.A, -\ J. Witt Groves, Esq. _ Joun ‘E. Inapen, Esq. Joun Marruews, Esq., M.D. ~ Joun Mavatt, Esq., Jun. _ Anpert D, Micwact, Esgq., FL. a. JouN Mintar, Esq., LRE.CP.Eadin., ELS. ‘Wirtiam Miruar Orp, Esq., M._D., F.R.C.P, Unpan Prrrcnanp, Esq., M.D. | Wrirramt THomas SUFFOLE, Esq. LIBRARIAN and ASSISTANT SECRETARY. Mr. Ja AMES Was. eee ea I. Numerical Aperture Table. NR ae * ’ The “ Aprrrurn”’ of an optical instrument indicates its greater or less capacity for receiving rays from the object and transmitting them to the image,/and the aperture of a Microscope objective is therefore determined by the ratio A between its focal length and the diameter of the emergent pencil at the plane of its emergence—that is, the utilized diameter of a single-lens objective or of the back lens.of a compound objective. : : This ratio is expressed for all media and in all cases by.n sin u, m being the refractive index of the medium and ~ the semi-angle of aperture. ‘he value of sin w'for any particular case is’the ‘‘numerical aperture” of the objective. Diameters of the ane g es Angle of Aperture (= 2 x). . Theoretical | pone ack Lenses of various Py Sa ee La Resolving suse Dry and Immersion Aperionl D < Water- | Homogeneous-| ‘nating | _ Power, in pee Objectives ob the Bamne (a Ae a.) | Obje aie es, | mmersion| Immersion | Power. | Lines toan Inch,| © ?W 0:72 © 56° 32’ | .-518 69,408 >| 1-389 — 0:70. ‘64° 50’ | -490| 67,480 | 17429 0:68 “5B° 9"| +462 65,552 | 1-471 | 0:66 51° 28" | +436] 63,624 | 1-515. 0:64 49° 48’ | +410}: 61,696 | 1-562 © 0:62 - 48°. 9'\| +384) 59,768 | 1-613 -0°60- 46° 30’ | +360} 57,840 | 1°667 ‘0:58 44° 51 | 8361 . 55,912) | 1-794" 0:56. ‘43° 14") «814 58,984. | 1:786 0:54 41° 37’ | +292 52,056 | 1°852- 0°52. 40°: 0' | +270] ° 50,128 | 1-923 “0°50 88° 24’-| +250 48,200. | 2-000. or their. HAMAS AURAU MERE SDAA RNAAGADRRCSERURUAMUNBNONEE RSS Ean Ape eS eS Seen: eer eee nee PTT TIT =) mm 900 m Suet 000433 000472 000512 000551 000591 000630 000669 000709 000748 000787 000827 000866 000906 000945 000984 001024 001063 001102 001142 | 2 001181 001220 001260 001299 001339 001378 “001417 *001457 001496 °001535 “001575 “001614 -001654 “001693 001732 “001772 001811 “001850 -001890. “001929 001969 002362 “002756 “003150 “003543 -003937 “007874 011811 “015748 “019685 “023622 027559 - +031496 5035433 19 21 39 =1 ete | 1000 (=I mm.) 20 @em.) 433075 472445 *D11816 *991186 “990556 *629927 “669297 "708668 “748038 *787409 “826779 +866150 “905520 “944890 “984961 1;023631 1:063002 1102372 1°141743 30 Bem.) 1°181113 1:220483 1-259854 1-299994 1°338595 1-377965 1417336 1:456706 1496076 1°535447 40 (4.em.) 1574817 1-614188 1°653558 1692929 1°732299 1:771669 1-811040 1850410 1°889781 1929151 “decim: 1 2 3 4 5 6 7 8 9 70 (Zem) ins, 3°937043 7°874086 11°811130 15°748173 19° 685216 23 * 622259 27° 959302 31°496346 39° 433389 10 (1 metre) 39-370432 IE 3°280869 ft. ©) od.cD. 09 G9 OD CO tO OD OED O0 Cy CN CO NO DD hD tb bo British and Metric Measures. 401596 440967 480337 519708 559078 998449 637819 677189 716560 795930 795801 834671 874042 913412 952782 992153 031523 070894 110264 149635 189005 998375 267746 307116 346487 385857 495998 464598 503968 543339 582709 3-622080 3° 661450 3+700820 3-740191 3°779561 3°818932 3858302 3°897673 50 (5 cm.) 1968522 | 100 (10 em,=1 decim,) 1°093623 yds. caliel CS pcs ae ee ht Olt cr as Bee Sse labels Co} S| © =| Sc} O}) 6} oO) ty) ii) je} ts Jol bh el Sika) | ol wugiiala stole pls Ce Crees eta ats ae as ahs aera mle C5 Bok | OHONIAor oboe lyd.= II. Conversion of ees 9 @.) Dinzan. Rae oaks Sele showing. Micromillimetres, &c., into Inches, Gc. Inches, &c., into the relation of oe fis mmc: ins, | mm, ins, idee -1 :000089|} 1 -039370| 51 2007892} ing oy 2 -000079! 2 “078741 | 52 “047262 | 2 4-015991 8 -000118|..38 ''. *118111| 58 086633 | <1” 4-969989 4. -000157| . 4 157482 | 54 126003 | 222" 4.693318 5 +000197| 5 196852 | 55 165374 | 3°" 9.539977 i 6 000236) 6 236223 | 56 204744 | 237" 9899197 7 000276! 7 275593 | 57 244115] 2°P? 3.474979 8 O03) 8 314963 | 58 283485 | "3° 3.98539 9 0003541. 9 |. -354384| 59 322855 | 1" 4-933995 10 -000394| 10 (Lem.) *393704| 6O(Gcem.) 2-362226) 2°" 5.079954 67349943 '8:466591 12°699886 25399772 mm. *028222 *031750 “036285 042333 - “050800 “056444 “063499 “:072571 -084666 "101599 -126999 “169332 -253998 “507995, 1-015991 1269989 1:587486 1-693318 2116648 2-539977 3°174972 4.933995 4762457 5079954 6349943 7937429 9:524915 cm, 1:111240 1°269989 ‘1°428737 1:587486 1: 746234 1°904983 2°063732 2:°222480 2°381229 2539977 5: 079954 F°619932 decim. 1:015991 1°269989 1°523986 1:777984 2.- (031982 2°285979 9:539977 2°7938975 3°047973 metres. *914392 C232) JOURNAL ‘OF THE ROYAL MICROSCOPICAL SOCIETY, ie ‘Containing ts ‘Crangactions and: Proceedings, _ AND a would occupy as long a time as would be required to insert a different eye-piece. Moreover, it is optically impracticable to make use of the same field-lens for B, C, and D eye-pieces. Francotte’s Camera Lucida.*—P. Francotte thinks that Beale’s camera lucida has a capital defect; the image is formed on the reflector too close to the eye-piece. The consequence is that the whole field is not visible at one time to the eye; whilst, for instance, the centre can be seen, the periphery is invisible; and in order to see all parts of the ficld, it is necessary to move the eye. Besides this, the short space left free between the eye-piece and the glass is very inconvenient. To obviate this he replaces the eye-piece by a single lens, giving an image which is reflected by an inclined glass plate or a mirror. The inclination of the reflecting surface may vary between 40° and 50°, according to the point of the table upon which the image is to be projected. The image is erect, and the whole field is included. The apparatus can be easily and very cheaply constructed. An ordinary lens (8 to 6 times) in a tube of cardboard is used as the eye- piece. The tube is cut obliquely, so that, on the elliptical section, a thin plate of glass or a mirror may be applied. On the upper surface an opening is made exactly over the place where the image is reflected. By adopting the same principle and replacing the large prism of * Bull. Soc. Belg. Micr., x. (1884) pp. 77-9. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 445 Oberhiuser’s camera by a mirror, the eye-piece by a single lens, and the small prism by a reflecting glass plate or a mirror, a convenient instrument is obtained which will not necessitate the inclination of the Microscope. Rogers's New Eye-piece Micrometer.*—“ Professor W. A. Rogers; of Harvard Observatory, has again laid microscopists under obligation by making an eye-piece micrometer for high oculars. It is a cover- glass of proper size to fit above the diaphragm of a 1/2 in. or 3/8 in. ocular, ruled in a scale with the fifth and tenth lines longer, and so fine as to need the magnifying power of the eye-lenses to separate the lines well. The high-power ocular separates also the striz of diatoms, or other minute subdivisions of objects, and the scale enables one to count them with a readiness and ease which has not before been possible. It is a simple and inexpensive thing, that takes the place of the most expensive spider-web micrometers.” Geneva Co.’s Nose-piece Adapters—Thury Adapters.—Prof. M. Thury takes exception to the remark at p. 284 that these adapters do not “ differ in principle from the nose-pieces of Nachet and Vérick.” The first adapter was, he says, made in October 1863 after his designs for Count Castracane, and another in 1865 for Prof. E. Clapa- réde. A Microscope exhibited by the Geneva Co. at the Paris Exhibition in 1867 was fitted with a similar adapter and was accompanied by a written description. At the 1878 Exhibition the modified movable form was exhibited. M. Nachet, who adopted the fixed form in 1877, “loyally termed it the ‘Pince-Thury.’” It was after the 1878 Exhibition that the movable form came to be made by others. Prof. Thury’s apparatus was evidently therefore the precursor of all such contrivances. Selection of a Series of Objectives.—Several writers have pub- lished their views on this subject, differing (with the exception of Dr. Carpenter) more or less from those put forward by Prof. Abbe in his paper on the “ Relation of Aperture and Power.” Dr. G, HE. Blackham f{ selects “asa set of powers sufficient for all the work of any microscopist the following :— One 4 in. objective of 0:10 N.A. = 12° air angle nearly. One I in. objective of 0:26 N.A. = 30° air angle nearly. One 1/6 in. objective of 0-94 N.A. = 140° air angle nearly. One 1/8 in. objective of 1:42 N.A. The first two to be dry-working objectives without cover correc- tion, the third to be dry-working with cover correction, and the fourth to be a homogeneous-immersion objective with cover correction, and all to be of the highest possible grade of workmanship. The stand... to be furnished with six eye-pieces, viz. 2 in., 1 in., and 3/4 in. Huyghenian, and 1/2, 1/3, and 1/4 in. solid. The following table * Amer. Mon. Micr. Journ., v. (1884) p. 52. + Proc. Amer. Soc. Micr., 6th Ann. Meeting, 1883, pp. 33-41, 227-31, 446 SUMMARY OF CURRENT RESEARCHES RELATING TO shows the application of these powers to all grades of work, from that which is ordinarily done with a pocket lens to the extreme limits of microscopical vision :— geSe| ¢ Arse | Bg pale N. A. required | Equivalent angular weg Bl ae How obtained. lin. to resolve. aperture. 2s = s Ba mies | ec & els 5 y, Objective. Hye-piece. 100\Less than 0:10/Less than 10° air} None |None |Naked eye Naked eye 500|Less than 0:10)Less than 10° air 5 1223/4 in. of 0°10 N.A.|2 in. §,000)Less than 0°10|Less than 10° air 50 50 |1 in. of 0:26 N.A./2 in. 10,000 0:11; 12° 38’ air 100 | 100 aD 1 in. 20,000 0:21) 24°16' ,, 200 | 200 As 1/2 in. 30,000 0°32) 37° 20’ ,, 300 | 300 |1/6in.of0°94N.A./2 in. 40,000 0:41) 48° 26’ ,, 400 | 600 i 1 in. 50,000 0°52} 62°40’ ,, 500 | 600 1 in. 60,000 0°63) 78° 08' ,, 600 | 600 1 in. 70,000 0°73} 938° 48’ ,, 700 | 800 3/4 in. 80,000 0°84) 104°17’ ,, 800 | 800 3/4 in. 90,000 0:94; 140° 16' ,, 900 {1200 1/2 in. 180° air, 82°17’ 96,000 1°00|; homogeneous 960 |1066 |1/8 in. of 1°42 |3/4 in. imm. fluid A. 100,000 1:04) 86°21’ ,, 1000 1066 a 3/4 in. 110,000 1°15} About 98°,, | 1100 |1600 é 1/2 in. 120,000 1:25} About 110°,, | 1200 {1600 5 1/2 in. 130,000 1°35) About 125°,, | 1300 {1600 Oc 1/2 in. 136,888 1:42) About 138°,, | 1368 |1600 ‘ 1/2 in. . . - It has not been my purpose to lay down any single set of objectives as the only proper one, but to indicate the principles on which selection should be made, and the relation of aperture to amplifying power, and to show that there is at present no good theo- retical reason for the use of objectives of greater amplifying power than the 1/8 in.” Dr. Blackham, it will be seen, advocates the use of eye-pieces as high as 1/4 in. which is largely in excess of Prof. Abbe’s figures, which do not go beyond an amplification of 15 times.* Mr. J. D. Cox believes} “ Dr. Blackham has the verdict of ex- perience with him when he says four or five lenses with a proper number of eye-pieces will cover the whole range of microscopical examination. In such a number of lenses you may get all the necessary combination of the three qualities of angle, power, and working distance which you may need. Different investigators may choose different series, but no one need have a greater number in the series. Economy is to be considered in deciding whether we shall choose one or another lens; but this is also consistent with the state- * See this Journal, iii. (1883) p. 808. + Proc. Amer. Soc. Micr., 6th Ann. Meeting, 1883, pp. 229-30. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 447 ment that all the elements, including economy, may be combined in such a small series. The lowest glass may be anything from a 1} in. toa3in. If of an angle of 20° to 25° it will have plenty of work- ing distance and penetration. The next glass should be of 40° angle, or very near it, as this is the maximum normal angle for binocular vision of opaque objects. Its working distance should be enough to allow the use of dissecting-needles under it, and the easy illumination of dry opaque objects. These conditions are found in good glasses ranging from 1 in. to 1/2 in. objectives. The third glass should also be a dry glass, having working distance enough to accommodate work with the animalcule-cages and compressors, and upon rough histological material. Its angle should be from 100° upwards, to as wide an angle as is consistent with the necessary working distance. These conditions are found in glasses ranging from 4/10 in. objectives to 1/6 in. Beyond the three lenses thus generally described, a single immersion lens of widest possible angle seems to give all the advantages that can be attained in the present condition of the art of making objectives. In the third and fourth of the series, the angle should be the widest consistent with the other conditions specially named, and this is the only demand of the practical microscopist in which, as it seems to me, the phrase ‘ wide angle’ can have any appropriate place.” Dr. J. Edwards Smith * says that he has practically, for the past four years, confined himself to the use of four object-glasses, namely, a lin. or 2/3 in. of 45° or 50°, a 1/2 in. of 38°, a 1/6 in. immersion, balsam angle ranging from, say 87° to 95°, according to the position of its collar, and a 1/10 in. immersion having a constant angle of 100°. Of the last two glasses, the 1/6 in. has a working distance of 1/50 of an inch. The 1/10 in. will work readily through covers 1/100 of an inch thick. A large amount of his work is on urinary deposits. For the examination of malignant growths and for minute pathology generally, a dry 1/4 in. of 100° is in reserve. Mr. EK. M. Nelson’s} view is to give the beginner a 14 in. anda 2/3 in.; later on a 1/6 in. may be added, and as a higher power a 1/12 in. immersion of 1°43 N.A. “For all working purposes the battery would then be complete, and the microscopist equipped to repeat any results hitherto obtained. As luxuries, a 3 in., 1/3 in., and 1/25 in. might be got. It sometimes happened that the high initial magnifying power of the 1/25 in. enabled the observer to find some hitherto unknown object, or portion of an object, more easily than with the 1/12 in.; but when once found its details of structure would be better made out with the 1/12 in. So far it had not been possible to construct a 1/25 in. as perfectly as a 1/12in., nor with so high an aperture ; hence it would rarely bear any eye-piece beyond the lowest. The 1/12 in., however, with proper manipulation, would bear the 1 in, eye-piece, and then reveal structure that could not be made out with 1/25’s, as hitherto constructed. * ‘How to see with the Microscope,’ 1880, pp. 202, 203, and 206. + Engl. Mech., xxxix. (1884) p. 48. 448 SUMMARY OF CURRENT RESEARCHES RELATING TO “‘Half-inch objectives had been made with apertures of 80°. Some authorities had declared that 40° was the highest aperture that could be usefully employed with that focal length. He had obtained one of the best examples of the 1/2 in. of 80°, and had made a careful series of trials with it. He had applied diaphragms above the back combination to cut down the aperture to 60° and 40° respectively, and the results might be briefly told. Taking the proboscis of the blow-fly and viewing it with the 1/2 in. diaphragmed down to 40° aper- ture, and arranging the illumination in the most favourable manner, he noted every detail of the picture, the sharpness and blackness of the points of the bristles, the transparency and clearness and general precision of the image; then removing the diaphragm behind the lens, he increased the aperture to 60°, and he found the image improved in every way. Increasing the aperture to the fullest extent, 80°, gave no advance upon the quality of image seen with 60° up to the 1 in. eye-piece; for this reason he concluded that 60° was the really useful aperture for a 1/2 in., and gave as much resolving power as the eye could well sustain with that combined power. No doubt the extra 20° would give the lens a higher resolving power with a stronger eye-piece, but he thought that might be better obtained with a lens of shorter focal length.” Mr. Nelson gives * the following table of apertures for object- glasses (with 1 in. eye-piece on a 10 in. tube), and says that “if ideal perfection is to be reached, the values given in the above table must be aimed at.” Tn. N.A. to) 3 90 708; aimangle.. =. =. == =. 20 2 ba 12, 3 Dr Gikmee stare LO 1} Ap ‘17, 5 sahipeats tap etek ot 20 1 . SOG Sateen cack! 2. ~ APaeee aes) 2/3 39, : vie etsy Sige ote cap Maus 1/2 52, 63 4/10 .. ‘65, . soot By wat) Ae eo V/A eee OEs os waterangle .. .. 103 1/5 .. 1°3, crown glassangle.. .. .. 117 1/6 .. 1:56, which has yet to be constructed. It will be seen that there is a wide divergence between Mr. Nelson’s and Prof. Abbe’s figures. For instance, for N.A. 0°65 Prof. Abbe suggests an objective of 1/8 in. and Mr. Nelson a 4/10 in. Lastly, we may give Dr. W. B. Carpenter’s views as expressed in his latest publication on the subject.} “The 1/8 in. is (according to the writer’s experience, which is confirmed by the theoretical deductions of Prof. Abbe) the lowest objective in which resolving power should be made the primary qualification,—the 1/6, 1/5, 1/4, and 4/10 in. being specially suited to kinds of biological work in which this is far less important than focal depth and dioptric precision. This view is strengthened by the very important consideration that the resolving power given by * Engl. Mech., xxxviii. (1883) pp. 367-8. + ‘Encyclopedia Britannica,’ 9th ed., xvi. (1883) pp. 269-70. ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 449 wide aperture cannot be utilized, except by a method of illumination that causes light to pass through the object at an obliquity corre- sponding to that at which the most divergent rays enter the objective. Now, although in the case of objects whose markings are only super- ficial such may not be productive of false appearances (though even this is scarcely conceivable), it must have that effect when the object is thick enough to have an internal structure; and the experience of all biological observers who have carried out the most delicate and difficult investigations is in accord, not only as to the advantage of direct illumination, but as to the deceptiveness of the appearances given by oblique, and the consequent danger of error in any inferences drawn from the latter. Thus, for example, the admirable researches of Strasburger, Fleming, Klein, and others upon the changes which take place in cell-nuclei during their subdivision can only be fol- lowed and verified (as the writer can personally testify) by exami- nation of these objects under axial illumination, with objectives of an angle so moderate as to possess focal depth enough to follow the wonderful differentiation of component parts brought out by staining processes through their whole thickness. The most perfect objectives for the ordinary purposes of scien- tific research, therefore, will be obviously those which combine exact definition and flatness of field with the widest aperture that can be given without an inconvenient reduction of working distance and loss of the degree of focal depth suitable to the work on which they are respectively to be employed. These last attributes are especially needed in the study of living and moving objects; and in the case of these, dry objectives are decidedly preferable to immersion, since the shifting of the slide which is requisite to enable the movement of the object to be followed is very apt to produce disarrangement of the interposed drop. And, owing to the solvent power which the essential oils employed for homogeneous immersion have for the ordinary cements and varnishes, such care is necessary in the use of objectives constructed to work with them, as can only be given when the observer desires to make a very minute and critical exami- nation of a securely mounted object.” A table is then given which in addition to the magnifying-powers of objectives with the A and B eye-pieces also “ specifies the angle of aperture which, in the writer’s judgment, is most suitable for each. He has the satisfaction of finding that his opinions on this latter point, which are based on long experience in the microscopic study of a wider range of animal and vegetable objects than has fallen within the purview of most of his contemporaries, are in accordance with the conclusions drawn by Professor Abbe from his profound investigations into the theory of microscopic vision, which have been carried into practical accomplishment in the excellent productions of Mr. Zeiss.” An extract from the table will be found on the next age. < 3 For ordinary biological work, the 1/8, 1/10, and 1/12 objectives, with angles of from 100° to 200°, will be found to answer extremely well if constructed on the water-immersion system.” Ser. 2.—Vo.. IV. 2H 450 SUMMARY OF CURRENT RESEARCHES RELATING TO Focal Angular Focal Angular Length. Aperture. Length. Aperture. in @) in. 2 4 9 1/4 50-80 3 12 1/5 95 2, 15 1/6 110 13 20 1/8 140 1 30 1/10 150 2/3 40 1/12 160 1/2 45 1/16 170 4/10 70 “Tt must be understood that there is no intention in these remarks to undervalue the efforts which have been perseveringly made by the ablest constructors of microscopic objectives in the direction of enlargement of aperture. For these efforts, besides increasing the resolving-power of the instrument, have done the great service of pro- ducing a vast improvement in the quality of those objectives of mode- rate aperture which are most valuable to the scientific biologist; and the microscopist who wishes his armamentum to be complete will provide himself with objectives of those different qualities as well as different powers which shall best suit his particular requirements.” “ High-angled” Objectives.j|—Dr. J. Edwards Smith “ prefers to regard as ‘ high-angled,’ any, and all glasses, without reference to their focal lengths, which are endowed with the widest apertures obtainable. If this be accepted, then it will occur that a 1 in. of 50° should be classed as a high-angled objective, and similarly a 2 in. of 25°. And, again, it would also then occur that a 1/6 in. of 130°, which fifteen‘years ago ranked as a wide, would now be classed as a glass of medium power.” Zeiss’s A* Variable Objective and “‘Optical Tube-Length.”— The demonstration of the important influence of “ optical tube-length ” on the magnifying power of the Microscope explains what has hitherto seemed a curious anomaly in the action of this objective. It will be remembered that it has a considerable range of power according as its two lenses are “ closed ” (when they are 44 mm. apart) or “open” (when they are at a distance of 52 mm.), the closing and opening being effected by rotating the collar on the objective. In the closed position the equivalent focal length of the objective is 54:1 mm., and in the open 389°7 mm., or a ratio of approximately 4:3. The power of the Microscope is however increased not in the ratio of 3: 4 only, but of 3 : 5:28. The explanation of this difference is found in the fact that A, or the optical tube-length, varies considerably according to the position of the lenses of the objective. When they are closed the posterior focal plane is 153:6 mm. from the back lens of the objective, but when open 125:7 mm. only. A is therefore (with a tube-length of 10 in. or 250 mm. from the back lens of the objective to the anterior focal plane of the ocular) 250 — 153-6 = 96°4mm.,or 250 — 125-7 = 124:3mm. + ‘How to see with the Microscope,’ 1880, p. 104. Cf. also p. 146. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 451 In the formula, therefore, for the magnifying power of the Micro- scope as a whole _ 250 A oe (f and @ being the focal lengths of the objective and ocular re- spectively), N is in the one case 17°8 and in the other 31°3, assuming @ to be 25 mm. Those who are interested in optical formule may like to have before them the method by which (1) the focal length of the objective and (2) the distances of its posterior focal plane are determined, accord- ing to the improved methods of Prof. Abbe, of which we hope to give a more detailed account later. (1) To determine the focal length f of the combination, we require to know only the focal lengths f, and f, of the two lenses, and the position of their anterior and posterior focal planes, whence we derive f according to the formula 2) eee rae (6 being the distance of the posterior focal plane of the first lens ¢ from the anterior focal plane of the second lens). Thus suppose in fig. 59 that we have given /, = — 24°8 mm. and Fig. 59. fF, = 48:4 mm., we require only to determine 6 to solve the equa- tion. We can determine é from the distances (supposed to be given) of the focal planes from the respective lenses, the distance of the posterior focal plane of the first lens F,* = 24:5 mm. and that of the anterior focal plane of the second lens F, = 46°3 mm. For the diagram shows that if from the total distance between F,* and the front of the second lens (which is made up of the variable distance between the lenses d and the quantity 24-5), we deduct the distance 46°3 mm. of the focal plane F, from the second lens we shall have the distance 6. + The first lens being a plano-concave the posterior focal plane (i. e. which relates to the posterior medium, or to the image) is in front of the lens, and not, as with convex lenses, at the back. 2H 2 452 SUMMARY OF CURRENT RESEARCHES RELATING TO Thus, according as the lenses are closed or open (d = 44 mm. or 52 mm.), 5 = 44 + 24:5 — 46°3 = 22°2 = §2 + 24°5 — 46°3 = 30-2. Having thus found 6, f is also found, as it is 24°8 x 48°4 "Qo. a mone or 24°8 x 48°4 _ g9.0 30-2 (2) The second step is to find the distance of the posterior focal plane F* of the combination, which being deducted from 10 in. gave us A. This distance, as the diagram shows, is made up of two quantities, one being the distance of the posterior focal plane F,* of the second lens, which is supposed to be given, and = 48-1 mm., and the other, an unknown quantity, which we will call ¢*. This unknown quantity may be determined from the known quantities of f, and 6 by the formula 2 cr = It is therefore =" = 105°5, or Gam according as the lenses are open or closed. Adding these values of ¢* to 48:1 we get the figures given above as the distance of the posterior focal plane from the back lens, i.e. 153°6 or 125°7. The focal length of the objective and the distance of its posterior focal plane are thus very readily found, without elaborate calculations, by simply knowing the focal lengths and the position of the focal planes of the separate lenses, data which can be obtained very simply and without the necessity of knowing anything about the formule on which the objective is constructed or the refractive index of the glass of which its lenses are made. We hope, as we have said, to return to this subject hereafter and in more detail. Queen’s Spot-lens Mounting.|—In order to overcome as far as possible the difficulty J. W. Queen and Co. have felt in fitting the spot-lens to instruments of various patterns (some with movable sub- stage and some with fixed tube, the latter at varying distances from the upper surface of the stage), they have devised the following mount :— The tube A (figs. 61 and 62) is made of standard size to fit the + Mier. Bulletin, i. (1884) p. 11 (8 figs.), ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 453 usual English and American substage or accessory tubes. The tube B carries a third tube C (blackened inside), sliding easily within it. Securely mounted in the latter tube is the spot-lens, which thus may be accurately focused upon the object; and when once adjusted for any stand, there is no occasion to alter it. If the small tubes be only 1/2 in. or 5/8 in. in length, the focusing range is a long one. Fig. 61. Fig. 60 shows the instrument as fitted to a Microscope which has the fixed tube beneath the stage. By reversing, as shown in fig. 61, the same mount may be used equally well in the movable substage of larger instruments. They have also applied the same device to the usual substage Society-screw adapter, for carrying achromatic condenser or objective used as such (fig. 62). The inside diameter of the tube C in this case is made 1} in., which will exclude very few objectives. It may, of course, be used, as the other, either in Microscopes with fixed stage tubes, or with movable substage. Paraboloid as an Illuminator for Homogeneous-Immersion Objectives.**—A. J. Moore attempts “to make two comparatively inexpensive pieces of apparatus take the place and do the work of any first-class wide-angled immersion condenser. These accessories are the ordinary parabola and the hemispherical lens.” Ordinarily the former is a dark-ground illuminator, but when the aperture of the objective exceeds that of the parabola, the effect is simply that of a dry condenser, in which the central rays are stopped out. But even at its best the light cannot traverse the slide at a greater angle than 41° from the axis; and it is rarely, if ever, even so great as this. Now, if the light reflected by the parabola could be converted into a glass (or balsam) angle without altering its angular direction, it would be amply sufficient to give light to the objective at the widest balsam angle now used in the best homogeneous- immersion objectives. ‘This may be done by using, under the slide, a hemispherical lens, whose radius is less than that of the concavity of the parabola, making optical contact by the immersion fluid. This is to be accurately centered and the parabola brought up so close that the hemispherical lens will occupy the concavity. When properly adjusted, it will be obvious that those rays which are transmitted by the parabola impinge normally to the surface of the hemispherical * «The Microscope,’ iv. (1884) pp. 27-30 (1 fig.). + This was described and figured by Mr. F. H. Wenham, Trans. Micr. Soc. Lond., iv. (1856) pp. 57-8 (1 fig.),—Ep. 454 SUMMARY OF CURRENT RESEARCHES RELATING TO lens, and hence are not refracted; that is, they traverse the same path in the lens that they had upon the parabola. The effect, then, is that of the wide-angled immersion condenser with the central rays stopped out. Although this may be very desirable for some objects, it is not generally so, and it becomes necessary to limit the direction from which the light comes. This may be very easily accomplished by the use of a cardboard diaphragm. This may be made by cutting a circle of blackened cardboard, the diameter of the inside of the mounting of the parabola, so that when pushed home against the glass surface the circle will be held friction-tight. By cutting small holes in this card the light may be regulated; and it should be kept well in mind that when the holes are cut in the outer edge of the card, the light, although oblique, will be more nearly central than when admitted to the reflecting surface through a hole nearer the centre; but should the hole be too near the centre of the card the light will not be transmitted at all, owing to the fact that it will strike the top of the concavity of the parabola. A good guide to go by is a circle upon the card whose diameter is the same as that of the top of the concavity. The most of the oblique light may then be obtained by cutting the holes near this line. Holes may be cut at various angles to each other, to effect the resolution of the various sets of lines by which some objects are marked. The author adds: “The chief objection to this method of illu- mination is, that central light cannot be obtained ; but this, of itself, is of no particular account, as the parabola may be removed from the substage when it is desired. As to the performance of this arrangement, I can speak in the highest terms; the resolution of the diatoms of Moller’s balsamed plate being easily ac- complished ; and when the full operation of the parabola was used, the dots of No. 18 showed better than I have ever seen them by any other method of illumination.” Paraboloid for Rotating Illumination in Azimuth.—We have a paraboloid with an arrangement shown in section in fig. 63. The bottom of the fitting is closed by a brass box in which is a rhomboidal prism, the lower face of which is over an oblong 4 slot in the centre of the lower plate of the box, while the upper face is towards the side of the upper plate, and just beneath the outer zone of the paraboloid. Over the upper face is a tube 14 in. high (the hori- zontal section of which is shown in fig. 64). Axial rays are, by means of the prism, made to fall on a part of the outer zone of the paraboloid, and by rotating the box can be brought into any azimuth of the latter. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 455 Horizontal Position of the Microscope. *—Mr. H. J. Slack con- siders that the usual position of a Microscope with a tube slanting a little and the head leaning forward to look down it, is all very well for a short examination of any object, but not at all desirable for continuous work. A better plan is to get a carpenter to make a light stool 2 ft. long and 14 in. wide, standing on four legs, the length of which should be determined by that of the Microscope it is intended to use and the height at which the observer sits. His own stool is 7 in. high, and when placed on an ordinary table brings a full-sized Microscope with its tube in a horizontal position at a convenient height for the eye of an observer sitting in an ordinary chair. The late Mr. Lobb, who was skilful in exhibiting troublesome objects, always used his Microscope in this position; but as far as Mr. Slack knows, it is seldom adopted. When the instrument is in position as described, the substage mirror should be turned cut of the way, and the lamp placed so that its flame is exactly opposite the axis of the instrument, and can be seen in the middle of the field on looking through it. If the objects to be watched are large enough for a low power, the light may be softened by placing under the slide a piece of foreign post paper saturated with spermaceti. For high powers, an achromatic condenser is desirable, and one of the smallest central stops is usually the most useful for displaying fine cilia, or delicate whips, as well as for lighting up without glare the interior of various creatures. If all is arranged properly, the manners and customs of infusoria may be watched for hours without more fatigue than reading -a well-printed book. A tenth part of the time spent with the head leaning forward in the usual way is far more exhausting. Flogel’s Dark Box.—Dr. J. H. L. Flogel some fourteen years ago devised the dark box, shown in fig, 65, to put over the Microscope and shut out all extraneous light. It is open behind and has an aper- ture in front to admit light to the mirror. From back to front it measures 20-25 cm., and in width 60-80 cm.; its height depends upon the stand to be used.{ He now adds a few words in the interest of those microscopists who may wish to have similar boxes made. t The principal thing is the right position of the aperture by which the light is admitted; its upper edge must lie exactly at the level of the stage—not lower, in order that the full light from the window may be used ; and not higher, in order that light may not fall from above on the stage, which would do away with most of the advantages of the box. The Microscope is put as far as possible in the box, so that the edge of the stage touches it, and, in order that there may be sufficient room for the head of the observer in this position, the anterior portion of the box is bowed out. On the right and left of the * ‘Knowledge,’ v. (1884) pp. 109-10. + Dr. L. Dippel considers this plan preferable to a darkened room with an opening in the shutter to admit light. The contrast between the illuminated field and the dark room is too great. The pupil of the eye is now enlarging and now contracting, and injurious results must inevitably follow. ‘Das Mikroskop,’ 1882, pp. 751-2 (1 fig.). t Zool. Anzeig., vi. (1883) pp. 566-7. 456 SUMMARY OF CURRENT RESEARCHES RELATING TO Microscope there should be enough room for the hands to move com- fortably and to be able to draw. The action of the dark box is that it strengthens the retina wonderfully in the perception of the finest details. ‘This takes place in two ways. First, in the ordinary mode of observing with the Microscope, the eye of the observer is so much disturbed by the light. from the illuminated eye-piece setting, and the surrounding objects, that many microscopists are accustomed to shade the eye with the hollowed hand as a remedy in delicate observation. This is obviated in the most perfect manner by the dark box. In the next place, it is by no means a matter of indifference whether strong or weak light- impressions are simultaneously received by the other open eye, which is at rest. Every more intense light-impression prejudices the sight of the other eye more than is commonly supposed. Into the dark box, however, only a faint illumination can enter from the light of the room behind it, especially when the table is black. Feussner’s Polarizing Prism.*—Dr. K. Feussner gives a detailed description of the polarizing prism lately devised by him, which presents several points of novelty, and for which certain advantages are claimed. The paper also contains an account, although not an exhaustive one, of the various polarizing prisms which have from time to time been constructed by means of different combinations of Iceland spar. I. Older Forms of Polarizing Prisms.—In comparing the various _ forms of polarizing prisms, the main points which need attention are :—the angular extent of the field of view; the direction of the * Zeitschy. f. Instrumentenk., iv. (1884) pp. 42-50 (8 figs.). See P. R. Slee- man in ‘ Nature,’ xxix. (1884) pp. 514-7 (8 figs.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 457 emergent polarized ray, whether it is shifted to one side of or remains symmetrical to the long axis of the prism; the proportion which the length of the prism bears to its breadth ; and, lastly, the position of the terminal faces, whether perpendicular or inclined to the long axis. These requirements are fulfilled in different degrees by the following methods of construction. 1. The Nicol Prism.*—This (fig. 66), as is well known, is con- structed from a rhombohedron of Iceland spar, the length of which must be fully three times as great as the width. The end faces are cut off in such a manner that Fic. 66. the angle of 72° which they originally form with the lateral edge of the rhombohedron, is reduced to 68°. The prism is then cut in two in a plane perpendicular to the new end surfaces, the section being carried obliquely from one obtuse corner of the prism to the other, in the direction of its length. The surfaces of this section, after having been carefully polished, are cemented together again by means of Canada balsam. A ray of light, on entering the prism, is separated by the double re- fraction of the calc-spar into an ordinary and an extraordinary ray: the former undergoes total reflection at the layer of balsam at an incidence which allows the extraordinary ray to be trans- mitted; the latter, therefore, passes through un- changed. This principle of obtaining a single polarized ray by means of total reflection of the other is common to all the forms of prism now to be described. é Dr. Feussner gives a mathematical analysis of the paths taken by the two polarized rays within the Nicol prism, and finds that the emergent extraordinary ray can include an angular field of 29°, but that this extreme value holds good only for rays incident upon that portion of the end surface which is near to the obtuse corner, and that from thence it gradually decreases until the field includes an angle of only about half the previous amount. He finds, moreover, that, although of course the ray emerges parallel to its direction of incidence, yet that the zone of polarized light is shifted to one side of the central line. Also that the great length of the Nicol—3-28 times its breadth—is not only an inconvenience, but, owing to the large pieces of spar thus required for its construction, prisms of any but small size become very expensive. To this it may be added that there is a considerable loss of light by reflection from the first surface, owing to its inclined position in regard to the long axis of the prism. It is with the view of obviuting these defects that the modifica- tions represented in figs. 67 to 71 have been devised. Mii pay MU Ly My Ny Mf * Kdin. New Phil. Journal, vi. (1828) p. 83. 458 SUMMARY OF CURRENT RESEARCHES RELATING TO 2. The Shortened Nicol Prism (fig. 67).—This arrangement of the Nicol prism is constructed by Steeg and Reuter of Homburg v. d. H. Fic. 67. Fia. 68. Fic. 69. For the sake of facility of manufacture, the end surfaces are cleavage planes, and the oblique cut, instead of being perpendicular, makes with these an angle of about 84°. By this alteration the prism becomes shorter, and is now only 2°83 times its breadth ; but if Canada balsam is still used as the cement, the field will occupy a very unsymmetrical position in regard to the long axis. If balsam of copaiba is made use of, the index of refraction of which is 1-50, a symmetrical field of about 24° will be ob- tained. A prism of this kind has also been designed by B. Hasert, of Hisenach,* but its performance appears to be inferior to the above. 3. The Nicol Prism with Perpendicular Ends (fig. 68).—The terminal surfaces in this prism are perpendicular to the long axis, and the sectional cut makes with them an angle of about 75°. The length of the prism is 3°75 times its breadth, and if the cement has an index of refraction of 1-525, the field is symmetrically disposed, and includes an angle of 27°. Prisms ofthis kind have been manufactured by Steeg, C. D. Ahrens, and others. 4. The Foucault Prism + (fig. 69).—This construc- tion differs from all those hitherto mentioned, in that a film of air is employed between the two cut surfaces as the totally reflecting medium instead of a layer of cement. The two halves of the prism are kept in position, without touching each other, by means of the mounting. The length of the prism is in this way much reduced, and amounts to only 1°528 times its breadth. The end surfaces are cleavage planes, and the sectional cut makes with them an angle of 59°. The field, however, includes not more than about 8°, so that this prism can be used only in the case of nearly parallel rays; and in addition to this the pictures which may be seen through it are to some extent veiled and indistinct owing to repeated internal reflection. 5. The Hartnack Prism} (fig. 70).—This form of prism was devised in 1866 by Hartnack and Praz- mowski, and was described, vol. iii. (1883) p. 428. It is considered by Dr. Feussner to be the most perfect prism capable of being prepared from calec- spar. The ends of the prism are perpendicular to its length; the * Poge. Ann., cxiii. p. 189. + Comptes Rendus, xlv. (1857) p. 288. } Ann. Chem. et Physique, vii. (1866) p. 181. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 459 section carried through it is in a plane perpendicular to the principal axis of the crystal. The cementing medium is linseed oil, the index of refraction of which is 1-485. The field of view afforded by this construction depends upon the cementing substance Fic. 70. used, and also upon the inclination of the sectional cut in regard to the ends of the prism; it may vary from 20° to 41°. If the utmost extent of the field is not required, the prism may be shortened by lessening the angle of the section at the expense however of interfering with the symmetrical disposi- tion of the field. 6. The Glan Prism * (fig. 71).—This is a modi- fication of the Foucault, and in similar manner includes a film of air between the sectional surfaces. The end surfaces and also the cut carried through the prism are parallel Fig. 71. to the principal axis of the calc-spar. The ends are normal to the length, and the field includes about 8°. This prism is very short, and may indeed be even shorter than it is broad. It is subject to the same defect as that mentioned in the case of the Foucault, although perhaps not quite to the same extent. Il.—Feussner’s Prism (figs. 72-8).—This prism differs very con- siderably from the preceding forms, and consists of a thin plate of a doubly refracting crystal cemented between two wedge-shaped pieces of glass, the terminal faces of which are normal to the length. The external form of the prism may thus be similar to the Hartnack, the calce-spar being replaced by glass. The indices of refraction of the glass and of the cementing medium should correspond with the greater index of refraction of the crystal, and the direction of greatest and least elasticity in the latter must stand in a plane perpendicular to the direction of the section. One of the advantages claimed for the new prism is that it dispenses with the large and valuable pieces of spar hitherto found necessary: a further advantage being that other crystalline substances may be used in this prism instead of calc-spar. The latter advantage, however, occurs only when the difference between the indices of refraction for the ordinary and ex- traordinary rays in the particular crystal made use of is greater than in calc-spar. When this is the case, the field becomes enlarged, and the length of the prism is reduced. The substance which Dr. Feussner has employed as being most suitable for the separating crystal plate is nitrate of soda (natron- salpeter), in which the above-mentioned values are w = 1-587 and * Carl’s ‘Repertorium,’ xvi. p. 570 and xvii. p. 195. + Amongst others, the modifications of the Nicol prism which have recently been devised by Prof. 8. P. Thompson (see this Journal, iii. (1883) p. 575), and by Mr. R. T. Glazebrook (Phil. Mag., 1883, p. 352), do not appear to have been known to Dr. Feussner. 460 SUMMARY OF CURRENT RESEARCHES RELATING TO « = 1:336. It crystallizes in similar form to calcite, and in both cases thin plates obtained by cleavage may be used. As the cementing substance for the nitrate of soda, a mixture of gum dammar with monobromonaphthalene was used, which afforded an index of refraction of 1°58. In the case of thin plates of calcite, a solid cementing substance of sufficiently high refractive power was not available, anda fluid medium was therefore employed. For this pur- pose the whole prism was inclosed in a short glass tube with air-tight ends, which was filled with monobromonaphthalene. In an experi- mental prism a mixture of balsam of tolu was made use of, giving a cement with an index of refraction of 1:62, but the low refractive power* resulted in very considerable reduction of the field. The extent and disposition of the field may be varied by altering the inclination at which the crystal lamina is inserted (fig. 72), and thereby reducing the length of the prism, as in the case of the Hartnack. Fia. 72. Fic. 73. a In order to obviate the effects of reflection from the internal side surfaces of the prism, the wedge-shaped blocks of glass of which it is built up may be made much broader than would otherwise be necessary; the edges of this extra width are cut obliquely, and suitably blackened. The accompanying diagram (fig. 73) represents a prism of cylin- drical external form constructed in this manner, the lower surface being that of the incident light. In this the field amounts to 30°, and the breadth is about double the length. - Dr. Feussner remarks that a prism similar in some respects to his new arrangement was devised in 1869 by M. Jamin,t who used a thin plate of calc-spar inclosed in a cell filled with bisulphide of * i.e. low as against 1°6585 the greater index of the calc-spar. + Comptes Rendus, Ixviii. (1869) p, 221. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 461 carbon; and also by Dr. Zenker, who replaced the liquid in M. Jamin’s construction by wedges of flint glass. The following tabular view of different forms of polarizing prisms is taken from the conclusion of Dr. Feussner’s paper :— Inclination of section Field. in regard to long axis. (o} to} I. Toe Op PouarRizinG PRISMS. 1. Nicol’s prism .. .. .. od 29 22 2. Shortened Nicol prism. a. Cemented with Canada balsam 13 25 , a » copaiba ,, 24 25 3. Nicol with perpendicular ends. a. With Canada balsam.. .. .. 20 15 b. With cement of index of refrac- 7 15 tion of 1:525 .. .. s. a) 4, Foucalt’s prism sarelteison cel amels 8 40 5. Hartnack’s prism. a, Original form .. .. .« « 35 13°9 b. With largest field .. .. .. 41:9 13°9 c. With field of 30° .. .. .. | 30 17°4 d. With field of 20° .. .. .. 20 20:3 @, Cllesiris (DARN 46 = ied 60 an ac 7:9 50°3 IJ. Frussner’s Pouarizing Prism. 1. With calc-spar: largest field 1 | 44 13°2 s 2 arey, x field of 30° 8 30 17'4 : Sawin FF field of 20° ee 20 20°3 0 4. With nitrate of soda : largest field 54 16°7 : By tars Hf 5, field of 30° 30 24 2°25 |72ab&73 Geo rs35 5 » field of 20° 20 27 : As an analysing prism of about 6 mm. clear width, and 13-5 mm. long, the new prism is stated by its inventor to be of the most essential service, and it would certainly appear that the arrangement is rather better adapted for small prisms than for those of considerable size. Any means by which a beam of polarized light of large diameter—say 3 to 35 in.—could be obtained with all the con- venience of a Nicol would be a real advance, for spar of sufficient size and purity for such a purpose has become so scarce, and there- fore so valuable, that large prisms are difficult to procure at all. So far as an analyser is concerned, the experience of Mr. P. R. Sleeman would lead to the opinion that improvements are to be looked for rather in the way of the discovery of an artificial crystal which absorbs one of the polarized rays than by further modifications depending upon total reflection. The researches of Dr. Herapath on iodosulphate of quinine * are in this direction; but crystals of * Phil. Mag., 1852, p. 161, and 1853, p. 346. 462 SUMMARY OF CURRENT RESEARCHES RELATING TO the so-called herapathite require great manipulative skill for their production. If these could be readily obtained of sufficient size, they would be invaluable as analysers. This opinion is supported by the existence of an inconvenience which attends every form of analysing prism. It is frequently, and especially in projecting apparatus, required to be placed at the focus of a system of lenses, so that the rays may cross in the interior of the prism. This is an unfavourable position for a prismatic analyser, and in the case of a powerful beam of light, such as that from the electric arc, the crossing of the rays within the prism is not un- attended with danger to the cementing substance, and to the surfaces in contact with it. Abbe’s Analysing Eye-piece.—This (fig. 74), devised by Prof. K Abbe, consists of a Huyghenian eye-piece with 1G. 74. : : : a doubly refracting prism P (a calc-spar prism achromatized by two suitable glass prisms) inserted between the eye-lens O and field- lens C, and over the diaphragm at B. The rays polarized parallel to the refracting edge pass through the prisms without deviation, whilst those polarized at right angles are strongly deflected, and are stopped off by a diaphragm over the eye-lens. The field of view remains undiminished. Measurement of the Curvature of Lenses.* —With very small lenses the spherometer can- & ans not be used, and Prof. R. B. Clifton’s method (Nu is based on the Newton’s rings formed between HM) the lens and a plane surface, or a curved surface TAI; of known radius. From the wave-length of the =m 4 light employed in observing and the diameter MMMM += of a ring the radius of curvature can be deter- mined. He places the lens on a plane or curved surface under a Microscope, and lights it by the sodium flame —wave-length 5892 x 10-’—measures the approximate diameters of two rings a distance apart (in practice the tenth and twentieth rings are found convenient), takes the difference of their squares, and divides it by the wave-length and the number of rings in the gap between to find the radius of the lens. The formula is :— p mr = (7 tn aa a”,,) where #,, + ,, and #, are the diameters of the nth and (m + n)th rings ; d is the wave-length of the light, and p' the radius of curvature of the lens. The method with proper care gives accurate results. Prof. Clifton has also used it to determine the refractive index of liquids in * “Nature, xxix. (1883) p. 148. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. . 463 small quantities ; Mr. Richardson having found it for water = 1°3335 by this method, which is usually correct to two places of decimals. It can also be used to determine if the lens is uniformly curved and spherical. New Microscopical Journals. Two new Journals have made their appearance. The first is the quarterly ‘ Zeitschrift fiir wissen- schaftliche Mikroskopie und fiir mikroskopische Technik,’ published at Brunswick, and edited by Drs. L. Dippel, M. Flesch, A. Wichmann, and W. J. Behrens. It embraces “Microscopy” in its widest sense, and includes original articles, abstracts and reviews, and a biblio- graphy of microscopical literature. It may be recommended to all microscopists who read German. The other is the bi-monthly ‘ Microscopical Bulletin,’ published by Queen and Co., of Philadelphia, which, though unpretentious, gives useful information on micro- scopical subjects. Bauscu, E.—A new Condenser. [Post.] The Microscope, IV. (1884) pp. 105-6. », Hye-pieces and Objectives. [General explanations. ] The Microscope, LV. (1884) pp. 107-12. Bausch and Lomb Optical Co.’s Improved “ Investigator ” Stand. [Cf. I. (1881) p. 100. Mirror and substage now swing independently, position of body-rack changed, &c.] Amer. Mon. Micr. Journ., V. (1884) p. 84 (1 fig.). Boun, C.—Ueber die Berichtigung des vereinfachten Ablese-Mikroskopes fiir Theilungen. (On the rectification of the simplified reading Microscopes for graduations. [Supra, p. 436.] Zeitschr. f. Instrumentenk,, LV. (1884) pp. 87-8. Bonp, G. M.—Standards of Length and their Subdivision. [Describes the Saxton Yard-dividing Comparator, the Rogers-Bond Universal Comparator, and a Comparator made by the Ballon Manufacturing Company for Professor Anthony. ] Journ. Franklin Institute, CX VII. (1884) pp. 281-95, 357-67 (5 figs.). BrapDBury, W.—The Achromatic Object-glass. XXXII.-V. Engl. Mech., XX XIX. (1884) pp. 93-4, 159-60, 246-7, 272 (6 figs.). “ CatcuLvs.”—Polarizer for the Microscope. [Simple contrivance to fit on tail-piece. ] Engl. Mech., XX XIX. (1884) p. 215 (1 fig.). Conepon, E. A.—Microscopy one hundred and fifty years ago. [Notes on ‘ Baker on the Microscope,’ 1740.] The Microscope, IV. (1884) pp. 74-6. 99 D., E. T.—Graphic Microscopy. IV. Pollen of Mallow. V. Peristome of Fumaria hygrometrica. Sci.-Gossip, 1884, pp. 73-4 (1 pl.), 97-8 (1 pl.). Davis, G. E.—(Leitz’s] Oil-immersion Objectives. Micr, News, IV. (1884) pp. 131-2, me a Evenings with the Microscope. I. [Measuring magnifying power of objectives and eye-pieces, and testing corrections of objectives. | Micr, News, TV. (1884) pp. 132-5. . Microscopy. Sci. Monthly, I. (1888) p. 26. 464 SUMMARY OF CURRENT RESEARCHES RELATING TO Firscu, M.—Welche Aussichten bietet die Hinfiihrung des elektrischen Lichtes in die Mikroskopie? (What prospect does the introduction of the electric light afford in Microscopy?) [Post.] Zeitschr. f. Wiss. Mikr., I. (1884) pp. 175-81. Hansen, E. C.— Ueber das Zahlen mikroskopischer Gegenstande in der Botanik. (On the counting of microscopic objects in Botany.) [Post.] Zeitschr. f. Wiss. Mikr., I. (1884) pp. 191-210 (6 figs.). Haziewoop, F. T.—A home-made revolving Table. [Post.] Amer. Mon. Micr. Journ., V. (1884) p. 94. Hircucocr, R.—Neglected Opportunities. [Exhortation to investigate the microscopic life of the country. ] Amer, Mon. Micr. Journ., V. (1884) pp. 95-6. x » A New Microscopical Society. [Sarcastic comment on the announcement of the establishment of the Ladies’ Microscopical Society at San Francisco having been first sent to England. “Trusting the members will learn that, although they may look to foreign lands for styles and methods of personal adornment, when they come to such a serious subject as microscopy, their wants can be as well met and their fame as well appreciated in their own country.”] Amer. Mon. Mier. Journ., V. (1884) p. 97. JaDANzA, N.—Sui sistemi diottrici compositi. (On compound dioptric systems.) Atti R. Accad. Sci. Torino, XIX. (1883) pp. 99-117. June, H.—Ueber ein neues Compressorium. (On a new Compressor.) [Post. Zeitschr. f. Wiss. Mikr., I. (1884) pp. 248-50 (2 figs.). Lancaster, W. J.—Lantern Microscope. [Directions for making. ‘You may make a lantern Microscope in half a dozen different ways, and the method to work upon will depend entirely upon the illumination you have. You state in query that you have the lime-light ; you could not have anything better. Fit up your Microscope in any form you like, and for object-lenses get three sets of lenses, A, two 14 in. focus, both plano, one 1/2 in., the other 3/4 in. diameter; B, two lenses both 1 in. focus, one 3/8 in. diameter, the other 5/8 in. diameter ; C, two lenses 3/4 in. focus, one 1/4 in., the other 1/2 in. diameter; and D, two lenses 1/2 in. focus, one 3/16 in., the other 3/8 in. diameter. Mount them in separate tubes in each case, both convex surfaces together, at the following distances apart :—A 1in., B 2/3 in., C 1/2 in., D5/16 in. ; then a stop must be placed in front of each of the smallest lenses, the larger lens going towards object. The sizes of stops and their distances from small lenses are as follows:—A, 1/8 in. diameter, 1/2 in. in front ; B, 3/32 in., 5/16 in.; C., 1/12 in., 3/16 in.; D,1/16in., 1/8 in.”] Engl. Mech., XX XIX. (1884) p. 152. Lomumet, E—Spectroskop mit phosphorescirendem Ocular. (Spectroscope with phosphorescent eye-piece.) [Post.] SB. KE, Akad. Wiss. Miinchen, 1883, p. 408. Magnifying Powers, Table of, with Note. Micr. Bulletin, I. (1884) p. 23. McCatua, A.—The “ Congress” Nose-piece. [Reply to Mr. Bulloch, ante, p. 300, with woodcuts of his original design. ] Amer. Mon. Micr. Journ., V. (1884) pp. 64-5 (3 figs.), 78-9. The Microscope, TV. (1884) pp. 101-2. Mercer, F. W.—A New Photomicrographic Camera. [ Post. ] Photography (Chicago), I. (1884) pp. 9-10 (1 fig.). MircHett, G. O.—A Focusing Glass for Photo-micrography. [Post.] Amer. Mon. Micr. Journ., V. (1884) p. 80 (1 fig.). Netson, E. M.—On the selection and use of Microscopical Apparatus. [Ante, p. 302, repeated here to give the following note:—(1) The Ross is decidedly to be preferred to the Jackson form, mainly on the ground of ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 465 the superiority of the long lever fine-adjustment over any other. (2) No Microscope is worthy to be called a scientific instrument unless it has a centering substage. (3) Choice and Aperture of Objectives, supra, p.447. (4) Eye-pieces. (5) Daylight, artificial light, and incandescence lamp, sepra, p. 447. (6) Condensers (Powell’s the ‘most effective for powers beyond 1/4). (7) Paraboloids, Lieberkuhns (post), Vertical illuminator, and Micrometers. (8) Polarization. (9) Diffraction and the difficulties of interpretation with objects requiring high magnifi- cation. ] ; Engl. Mech., XX XIX. (1884) p. 48. Noe, L. H.—Homogeneous immersion. [‘‘It seems to me that to make a lens which shall work through different thicknesses of cover-glass equally well and without adjustment, the immersion medium should correspond with the cover-glass, so that the combined thickness of glass and immersion fluid would always be the same (although the thickness of each varied) for an object in contact with the under side of the cover.’’] Amer. Mon. Micr. Journ., V. (1884) p. 79. “Nor an Optictan.”—Theory of the Achromatic Object-glass. [Comments on O. V.’s articles. ] Eng. Mech., XX XIX. (1884) p. 210. “ OrpERIC ViTAL.”—The Dialyte and Plate Glass. Lingl. Mech., XX XIX. (1884) p. 215. Ort, J._-Cursus der normalen Histologie zur Einfiihrung in den Gebrauch des Mikroskopes sowie in das practische Studium der Gewerbelehre. (Course of normal Histology as an introduction to the use of the Microscope as well as to the practical study of Histology.) 3rd ed., xii. and 340 pp., 108 figs. 8vo, Berlin, 1884. PEAUCELLIER.—Note sur la déformation des images réfractées et sur l’aplanatisme d’un systéme de lentilles. (Note on the distortion of refracted images and on the aplanatism of a system of lenses.) Mém, Soc. Sci. Bordeaux, V. (1883) pp. 327-34 (1 pl.). PERAGALLO, H.—Histoire sommaire du Microscope composé et de ses récents perfectionnements. (Compendious history of the compound Microscope and its recent improvements.) 8yvo, Toulouse, 1883. Puran, F.—Apparat zur Priifung der Brennweite des Auges oder anderer optischer Systeme. (Apparatus for testing the focal length of the eye or other optical systems.) Title only of German Patent, Cl. 42, No. 1894, Feb. 1884. “« PRISMATIQUE.”—Plate Glass for Optical Purposes. Engl. Mech., XX X1X. (1884) pp. 191-2, 281. Proctor, R. A.—Review of Poulsen and Trelease’s ‘ Botanical Micro-chemistry,’ in which the invention of the achromatic microscope-objective is attributed to J. J. Lister in 1829! Knowledge, V. (1884) p. 231. Pusoner & WIEDERHOLD.—Cementing Brass on Glass. [Puscher recommends a resin soap for this purpose, made by boiling 1 part of caustic soda, 3 parts of colophonium (resin) in 5 parts of water and kneading into it half the quantity of plaster of Paris. This cement is useful for fastening the brass tops on glass lamps, as it is very strong, is not acted upon by petroleum, bears heat very well, and hardens in one- half or three-quarters of an hour. By substituting zine white, white lead, or air-slaked lime for plaster of Paris, it hardens more slowly. Water only attacks the surface of this cement. Wiederhold recom- mends, for the same purpose, a fusible metal composed of 4 parts of lead, 2 parts tin, and 23 parts bismuth, which melts at 212° Fahr. The melted metal is poured into the capsule, the glass pressed into it and then allowed to cool slowly in a warm place. ] Polyt. Notizblatt. See Engl. Mech., XX XIX. (1884) p. 119. RetcuertT, C.—Anleitung zum Gebrauche des Mikroskops. (Introduction to the use of the Microscope.) 14 pp. (2 figs.), 8vo, Wien, 1883, ae Ser. 2.—Vot. IV. 2-F 466 SUMMARY OF CURRENT RESEARCHES RELATING TO Scort, G. B.—Polarizer for the Microscope. [Analyser mounted in a tube on a swivel just over the nose-piece so that it can be “ pushed over to one side out of the way by a lever” when not in use. Polarizer also mounted on a short arm beneath the stage. Micro- scopes with narrow tubes must have a recess into which the analyser can 0. gerd Engl. Mech., XX XIX. (1884) p. 173 (2 figs.). Srrmn, T.—Die Verwendung des elektrischen Gliihlichtes zu mikroskopischen Untersuchungen und mikrophotographischen Darstellungen. (The application of the electric incandescence light for microscopical investigations and photo- micrography.) [Post.] Zeitschr. f. Wiss. Mikr., I. (1884) pp. 161-74 (7 figs.). SroweE., C. H.—Our third Annual Soirée. The Microscope, LV. (1884) pp. 63-4. BS 5p An Editor’s Life. [Letter from a microscopist who “ finds the working of the Microscope very pleasant employment for the evening of life.” ] The Microscope, LY. (1884) p. 105. Swammerdam, John, Sketch of his Life and Researches. Journ. of Sci., VI. (1884) pp. 198-206. Tait, P. G.—Light. viii. and 276 pp. and 49 figs. [Microscope, pp. 113-6.] 8vo, Edinburgh, 1884. Vocrt, J.—Das Mikroskop und die wissenschaftliche Methode der mikro- skopischen Untersuchung in ihrer verschiedener Anwendung. 4thed. By O. Zacharias. Lfg.1. Leipzig, 1884. Wanscuarr, J.—Ueber eine neue Methode zur Anfertigung sehr langer Mikro- meter-schrauben. (On a new method of constructing very long micrometer screws. [Post.] Zeitschr. f. Instrumentenk., LV. (1884) pp. 166-9. Warp, R. H.—An Eye-shade for Monocular Microscopes. [Post.] Amer, Mon. Micr. Journ., VY. (1884) pp. 82-3 (1 fig.). WassELL, H. A.—Plate Glass for Optical Purposes. Engl. Mech., XX XIX. (1884) pp. 170-1. WiEDERHOLD.—See Puscher. ZacHaRiAs, O.—See Vogel, J. B. Collecting, Mounting and Examining Objects, &c. Dissection of Aphides.*—G. B. Buckton says that “in the dissection of Aphides much assistance may be often got by a selection of liquids. Some of these are best suited for the purpose of hardening the tissues, so that they may bear separation and tearing asunder without their destruction. Others are used for colouring the trans- parent organs, so as to make them more visible. These organs of Aphides are so delicate that pure water will in a great measure destroy them. In such cases a weak solution of common salt, or very dilute glycerine, or sugar and water, or albumen and water, all of which should nearly approach the density of the juices of the insect, will be found a considerable help. Some Aphides are so large, so full of liquid, and so charged with oil-globules that some treatment is necessary to reduce their bulk, and to allow of a sufficiently thin stratum of balsam for mounting. In such cases the Aphides may be placed in spirits of turpentine, and just raised to the boiling-point in a small test-tube. After soaking in the turpentine for a few hours, all the oil-globules will be removed, * ‘Monograph of the British Aphides,’ iv. (1883) pp. 193-5. ZOOLOGY AND BOTANY, MIOROSCOPY, ETC. 467 and the insect by this treatment will have become transparent, and the aqueous parts will not then chill the balsam. To prepare Aphides for dissection, liquids may be divided into those used for hardening the tissues and those employed for colouring the same. For hardening, a digestion for several hours in weak alcohol will be of advantage. The alcohol must not be too strong, or the albuminous portions will be coagulated and become too opaque. Weak acetic acid will render some portions tough, and the same action is also well effected by a weak solution of phosphoric or of nitric acid. The action of ordinary ether upon Aphides is not well understood. Their bodies are speedily destroyed by plunging them into the liquid. At the same time a considerable stream of air-bubbles contained in the traches is expelled, and of such a volume as would lead to the suppo- sition that much of this air must be in some state of solution in the body-juices. The reaction of weak potash has been before noted. As a rule, the germinal matter resists its action for a considerable time. Simulta- neously this reagent usually stains it a bright gamboge yellow. In some genera (notably Sachuus and Dryobius) potash deepens very markedly the violet dye natural to these Aphides. In other cases I shave found potash to evoke the violet shade from specimens otherwise colourless. This dye is fugitive, and if discharged by an acid, cannot be again recovered by the action of an alkali. Soda and ammonia also bring out this colour. Advantage may be taken of the fact that there is a certain order in which the tissues resist the intrusion of a foreign matter such as a dye. Thusthe germinal and most vitally endowed organs reject dyeing by carmine, logwood, and such coal-colours as magenta; whilst the portions in process of exfoliation and decay absorb it the most readily. For such purposes, weak alcohol may be made slightly alkaline by ammonia, and tinged with a little carmine or cochineal solution. Dilute chromic acid both tinges the tissues yellow and renders them tough. Solutions of osmic acid also may be used with advantage, and, in short, the usual reagents employed for conducting minute anatomy may be taken with due circumspection and tenderness. For labelling specimens, paste will be found much more adherent than gum. The former may be preserved for some months in a well- closed bottle, if a little aqueous solution of corrosive sublimate be stirred into it.” Transmission, Preservation, and Mounting of Aphides.*—G. B. Buckton gives the results of his experience as to the best mode of transmitting living Aphides, and also the best method for killing and preserving such-like insects for future examination. As to transmission, the chief thing to be guarded against is desic- cation, and no plan seems to be so successful as their inclosure in ordinary quills stopped by plugs of cork or pellets of beeswax. The substance of the quill is sufficiently porous to prevent mildew on the * ¢‘Monogiaph of the British Aphides,’ iv. (1883) pp. 188-93. 2h 2 468 SUMMARY OF CURRENT RESEARCHES RELATING TO one hand and a rapid evaporation on the other. In this way small insects may be sent through the post, and in a far better condition than can be secured in any tin boxes, even though they be filled with leaves. Ifa slip of some succulent leaf be rolled round each quill, to retain moisture, a bundle will conveniently pass through the post. For preservation (other than on a slide) the best plan is to drop the insects into small flattened glass tubes partially filled with a suitable liquid, then draw the tube to a fine point, break the end off, and warm the empty space (or, better, expel the air by a pump), and the tube can be entirely filled with liquid, and then sealed with the blowpipe. For mounting microscopically, five or a dozen spots of fluid Canada balsam should be dotted on a slide from the head of a pin, and by means of a hair pencil as many living insects transferred to them. “The specimens at once adhere, and if the spots are small the insects spread out their limbs naturally, with a view to escape. They may be fixed on their backs or otherwise, according to the views desired. A very thin glass cover, or, if very high magnifying powers are wanted, a small disk of clear mica, is laid over the insects, and then one or more drops of the fluid balsam are delivered from a glass rod at one of the sides of these covers. The balsam runs slowly under by capillarity, and it drives all the air before it, the small weight of the cover assisting it to spread, until the whole area is filled. No pressure is to be used, or the elastic bodies of the Aphides will change shape; and besides this, the juices will be forced through the cor- nicles and pores. If the balsam is thick, a very gentle heat, hardly exceeding that of the cheek, may be applied, but as a rule the tempera- ture of a room is better than that which exceeds it. The insects die immediately they are cut off from air, and in almost every case their position will be good for examination. To spread the wings of a small insect, the above-mentioned small dots may be made in a row. The belly of the specimen is applied to the middle spot, and by a bristle one wing may be applied to the dot on the one side, and the other wing to the third dot. The cover is then placed as before, and when the balsam runs in it will not disturb the position of the spread wings. It will be noticed that very soon after live insects have been mounted in a resinous substance that will not mix with water, a white cloudiness forms around each specimen. ‘This is caused by the watery juices of the insect, which ‘chill’ the medium and make it opaque. This cloudiness, however, entirely disappears after perhaps a month, the moisture being carried slowly outwards. The same is to be said of stray air-bubbles. The oxygen of the air unites with the balsam, and thus hardens it; but what combination is effected with the nitrogen is not so clear. However, air-bubbles in balsam disappear in time, provided the former is not in too hard a condition. In cases when the above small pressure is undesirable, small circles, cut by round punches of different sizes out of very thin sheet ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 469 lead, will be found more convenient to insert between the glass slip and its cover than circles of card, which are sometimes recommended. The thin sheet lead from the Chinese tea-chests is very suitable for punching, and as it is not porous like card, it yields no air-bubbles by heat. : D. Von Schlechtendal has* described a method by which it would appear that all the characters of form and colour (?) may be preserved in Aphides and other insects. The method consists of a rapid death and drying of the insect by means of a current of heated air. The Aphis, previously attached to some suitable support, is suddenly and momentarily subjected to the heat of a spirit or other flame, by which it is immediately killed and caused to retain its natural position. Several examples are then carefully roasted in a current of hot air, such as that passing through an inclined glass tube duly made hot, or dried on a sheet of paper moved over a heated metal plate. When dry, the specimens are mounted on card by attachment with gum tragacanth; or, as Mr. T. W. Douglas suggests, more con- veniently on mica, called ‘talc, in the shops, which, as it is incom- bustible, is well suited for a support both before and after drying. This method is vouched for as good by Drs. Giebel, Taschenburg, Mayr, and Rudow. I have not tried this roasting process, but it must require some address to prevent the shrivelling of wings in such delicately-formed insects, and to provide against the bursting action of the boiling juices. A more complete history of the process than the foregoing was given by Mr. Douglas in 1878.7 M. Lichtenstein has many times been good enough to forward in letters to me preparations of Aphides which have been secured between two films of mica. ‘The insects, he explains, are immersed in a solution of resin in turpentine, ‘a natural amber,’ and, when all are in due position, the mica films are placed over apertures in card, and then gummed papers, similarly perforated, are pressed upon them. This arrangement secures all in their places. Methods and operations in science, like events in history, repeat themselves. Fifty years ago films of mica were used to cover objects for the Microscope, and before the manufacture of the thin glass now so commonly used, it admirably answered its purpose. Under deep magnifying powers, such as 1/12 in., it will be found even now of great service. The mineral may be split by the lancet into films much thinner than glass can be blown in a flat state. Small un- scratched pieces may be selected which are perfectly transparent, and their cost is quite trifling. On account of the high refracting power of Canada balsam, the colours of recently-immersed Aphides show themselves very brightly; and it sometimes happens that tints, quite lost through irradiation or glance on the surfaces, become distinct by treatment with this resin. The bright colours and markings of some species are due to the * Entomol], Nacbrich., iv. p. 155. + Entomol. Mon. Mag., xv. p. 164. 470 SUMMARY OF CURRENT RESEARCHES RELATING TO hue of the internal juices of the insects. These cannot be preserved by balsam, but it is otherwise with the pigments which stain the somewhat horny coverings of the thorax and abdomen. These colours are persistent.” Breckenfeld’s Method of Mounting Hydre.*—A. H. Breckenfeld describes the following process as accomplishing the desired end more perfectly than any other published. Have in readiness a slide upon which a well-dried cell of sufficient depth has been turned. Then, from a gathering of Hydra, transfer a sufficient number of individuals (the more fully developed the better) very carefully, by means of a camel’s hair brush or a pipette, toa drop of water spread near the end of a plain glass slide, and place the latter upon a table in such a way that the end with the drop projects about two inches over the edge. This is easily done by placing a weight upon the oppesite end. After allowing the slide to remain perfectly undisturbed for three or four minutes, hold a lighted coal-oil lamp so that the top of its chimney is very near the slide, but a trifle above it. The Hydre will then appear brightly illuminated, and it can easily be determined by the unaided eye whether or not their tentacles are fully extended. If they are, quickly move the lamp directly under the drop, with the top of the chimney about an inch beneath the slide, and hold it in that position for about 3-5 seconds, the exact time depending principally upon the intensity of the heat. Then quickly remove the slide and place it upon a slab of marble or metal. When cool, pour the drop containing the zoophytes into the prepared cell on the slide which has been held in readiness, add a drop or two of a suitable preservative fluid, arrange the animals, if necessary, by means of a needle or camel’s hair brush (using very great care, however, as the tentacles will be destroyed by the least rough handling), cover with thin glass, and finish as in the case of any fluid mount. This “hot water” process seems to succeed peculiarly well with the brown Hydra (H. vulgaris). Cell-sap Crystals.|—Crystals of the colouring material present in the petals and other portions of plants are by no means common or, as a rule, easy to obtain; and G. Pim thinks it may therefore interest some to know that the rich violet-coloured cell-sap in the flower of Justicia speciosa, a common and easily-grown stove-plant, crystallizes very easily into minute slender prisms. To obtain them it is only necessary to mount a fragment of the flower-stamen for choice, in dilute glycerine jelly, not too hot, without any previous treatment ; after a few hours the colouring material collects into a few cells, in the form of the crystals above mentioned, forming a very pretty and interesting object for a 1/4 in, objective. Staining for Microscopic Purposes.,—H. Gierke contributes a paper on this subject. In the first part, after an excellent introduc- * Amer. Mon. Micr. Journ., v. (1884) pp. 49-50. +-Journ. of Bot., xxii. (1884) p. 124. t Zeitschr. f. Wiss. Mikroskopie, i. (1884) pp. 62-100. See Bot. Centralbl., XVili. 1884) p. 52. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 471 tion, the writer gives an historical review of the application of micro- chemical methods of staining, giving special attention to the carmine- pigments. The earliest experiments on microscopic staining with carmine for the purpose of a ready differentiation of tissues were made by Goeppert and Cohn. More extended investigations on the capability of the various elements of vegetable tissues to fix carmine shortly followed by R. Hartig. In animal histology, carmine staining was first employed by Gerlach (1858). Further contributions to its application were made especially by Maschke, Thiersch, Beale, Rollen, Gwancher, Hoyer, Czokor, Ranvier, and others. Reference is further made to the cultivation of cochineal, and to the most con- venient methods of obtaining carmine for technological purposes, and its application as a staining material in the form of ammonium car- minate, and carmine acetate. The author convinced himself by ex- periments that old preparations of ammonium carminate, which contain a certain quantity of ammonium carbonate, stain better than fresh solutions. Finally, a shorter reference is made to the aniline-dyes, hematoxylin, indigo-carmine, and picro-carmine. The second part includes a chronological and tabular account of the literature of the subject, especially with regard to the following staining materials :—(1) carmine; (2) hematoxylin; (3) ammonium molybdate ; (4) alizarin and purpurin; (5) alcanna and lakmus; (6) sodium indigo-sulphate (indigo-carmine). Mode of announcing new Methods of Reaction and Staining.* —E. Giltay calls attention to the fact that the publication of new methods of reaction is often made without sufficient precision for others to be able readily to form a judgment on their applicability for the special purpose. In the description of the application of a reagent, at least one mode of preparing it ought to be accu- rately described, such expressions as ‘somewhat,’ “ a little,’ “a short time,” and such like, should be avoided, and replaced by exact statements of weight and time. In the case of little known sub- stances, the chemical formula—intelligible-in all languages—should be appended. ‘The descriptions of colours should be as correct as possible, with reference to all influencing circumstances, and should be based on some definite colour-scale, such as that of Chevreul’s ‘Des Couleurs.’ Pure Carminic Acid for Staining.,—G. Dimmock has often won- dered why naturalists use carmine solutions in which water, with some caustic or destructive material added, is the principal solvent. Carmine of commerce, it is true, is not readily soluble, even in water, until ammonia, borax, or some other aid to solution is added ; but car- minic acid, the basis of the colouring matter of carmine, has long been stated in the leading chemical dictionaries and handbooks to be readily soluble in water and in alcohol. Watts (Dict. Chem., 1872, 1st suppl., p. 413) says of carminic acid :—“ This acid forms a purple * Zeitschr. f. Wiss. Mikroskopie, i. (1884) pp. 101-2. + Amer. Natural., xviii. (1884) pp. 324-7. 472 SUMMARY OF CURRENT RESEARCHES RELATING TO mass, fusible and soluble in all proportions in water and in alcohol. Sulphuric and hydrochloric acid dissolve it without alteration. It bears a heat of 136° C. without decomposition.” Larlier still Watts. (Dict. Chem., i. 1863, p. 804) says:—“ The fine red pigment known in commerce as carmine is prepared by treating a solution of cochineal with cream of tartar, alum, or acid oxalate of potassium. The fatty and albuminous matters then coagulate and carry down the colouring matter with them.” Now in preparing most carmine solutions this precipitation takes place, and the carmine, having greater cohesive (not chemical) affinity for impurities of animal origin than for alcohol, its solution is not readily accomplished by that medium, nor indeed by water. In preparing carmine solution for histological purposes by some of the published recipes, more than one-half of the colouring matter of the carmine is lost in the refuse left upon the filter aper. ‘ “igs are two ways commonly in use for preparing carminic acid. The first mode is that of De la Rue, which Watts (Dict. Chem., i. 1863, p- 804) gives as follows :—“ To separate carminic acid, cochineal is exhausted with boiling water; the extract is precipitated by subacetate of lead slightly acidulated, care being taken not to add the lead-solu- tion in excess; the precipitate is washed with distilled water till the wash-water no longer gives a precipitate with a solution of mercuric chloride, then decomposed by sulphuretted hydrogen ; the filtrate is evaporated to a syrupy consistence and dried over the water-bath ; and the dark purple product thus obtained is treated with alcohol, which extracts the carminic acid.” The second mode is that of C. Schaller and is given by Watts (Dict. Chem., 1st suppl., 1872, p. 413) as follows :— “‘Schaller prepares this acid by precipitating the aqueous extract of cochineal with neutral lead acetate slightly acidulated with acetic acid ; decomposing the washed precipitate with sulphuric acid ; again pre- cipitating the filtrate with lead acetate, and decomposing the precipi- tate with hydrogen sulphide. The filtered solution is evaporated to dryness; the residue dissolved in absolute alcohol; the crystalline nodules of carminic acid obtained on leaving this solution to evaporate are freed from a yellow substance by washing with cold water, which dissolves only the carminic acid ; and the residue left on evaporating the aqueous solution is recrystallized from absolute alcohol or from ether.” Schaller’s mode of preparation gives purer carminic acid than De la Rue’s, but either kind is sufficiently pure for histological purposes. The precipitation by lead acetate and the dissolving in alcohol free the carminic acid from animal impurities, and the consequence is a purer form of pigment than can be extracted by any process hitherto employed for the preparation of carmine for histological purposes. It is unnecessary to explain to naturalists the advantages of alco- holic solutions of carmine over aqueous ones. The alcoholic solution colours preparations much quicker than the aqueous solution does ; for colouring sections, the author employs a solution of 0:25 gr. car- minic acid to 100 gr. of 80 per cent. alcohol, and leaves sections in the ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 473 solution from two to five minutes. A solution of equal carmine strength but in absolute alcohol can be employed ; it has, however, no special advantages, since with the 80 per cent. alcoholic solution the sections can be washed directly in absolute alcohol, and then put into oil of cloves or turpentine. Colouring in the piece before sectioning never takes as long with alcoholic carminic acid as it does with ordi- nary carmine solutions, and if it did take long the strong alcohol would preserve the tissue from maceration. In colouring pieces of mollusea, or of other equally slimy animals, the slime should be removed beforehand, or the staining will be unsatisfactory, because the slime congealing in the alcohol takes up the colouring matter, forming an almost impervious coloured layer on the outside and leaving the inside of the piece nearly uncoloured. Some preparations coloured in alcoholic carminic acid and then put up in glycerine lost their colour in a few months, the colour seeming to be entirely diffused in the glycerine, while similar prepara- tions mounted in Canada balsam retained their colour perfectly. The author does not know if this fading would occur with preparations coloured with alcoholic ammonic carminate, or even if this diffusion was not due to some impurity of the glycerine (of the purity of which he was doubtful) ; time to test this matter further failed. An alcoholic ammonic carminate, or ammonia carmine, can be pre- pared, at a moment’s notice, from alcoholic carminic acid, by adding ammonia drop by drop, and stirring until the entire solution changes from its bright red to purple red. By this mode pure alcoholic ammonic carminate can be produced with no excess of ammonia, and at any time. As the carminic acid can be preserved dry without decomposition, and dissolves quickly in alcohol, one can carry the ingredients of a carmine solution in the vest pocket without incon- venience. In making and using alcoholic carminic acid pure alcohol and distilled water give the best results, because a portion of the carminic acid is converted to carminates by the salts of impure water. In making alcoholic ammonic carminate this precaution is not as neces- sary, because the colour of the carminates produced by the impurities of the water is so nearly like that of ammonic carminate. Alcoholic carminic acid may be used, as Grenacher’s carmine solu- tion is used, to colour sections from which the colour is to be afterwards partly extracted by very dilute hydrochloric acid, leaving nuclei red. Another way to use carmine solutions, which is especially applicable to alcoholic carminic acid, is to precipitate the carmine in the tissues by some salt, the carminate of the base of which gives a desired coloration. For example, specimens hardened for a moment under the cover-glass with an alcoholic solution of corrosive sublimate (mer- curic chloride) and, after washing with alcohol, coloured in alcoholic carminic acid, take a fine colour of mercuric carminate. So, too, specimens coloured in alcoholic carminic acid can be changed by a few moments’ treatment with a very dilute alcoholic solution of lead acetate or cobalt nitrate to a beautiful purple. Sometimes salts in the 474 SUMMARY OF CURRENT RESEARCHES RELATING TO {issues of the animals change portions of the carminic acid to purple carminates, giving a double coloration without further treatment. Picric acid added to alcoholic carminic acid in extremely small quantities (best in a dilute alcoholic solution, testing the solution on specimens after each addition) makes a double alcoholic colouring fluid (a so-called picro-carmine). The author has been unable thus far to determine the proportion of picric acid required for this solution, having in every case added an excess. All different kinds of carmine solutions can be made from carminic acid with the advantage of having always uniform strength, of being definite mixtures, and of not spoiling as readily as those made directly from cochineal. Incompatible reagents with carminic acid are, of course, all alka- line solutions and nearly all metallic salts; with ammonic carminate, are naturally all acids; with all carmine solutions, are bromine and chlorine. Hoyer’s Picro-Carmine, Carmine Solution, and Carmine Powder and Paste.*— Hoyer proposed + an improved picro-carmine made by dissolving his carmine powder in a concentrated solution of neutral picrate of ammonia. P. Francotte points out that picrate of ammonia is a substance which it is not possible to have constantly at hand, and he has therefore modified Hoyer’s preparation in the following manner :—Dissolve 1 gr. of carmine in from 5 to 7 ¢.cm. of concen- trated ammonia, diluted with the same amount of water ; in 50 c.cm. of distilled water dissolve (warm) 1/2 gr. of picric acid ; mix the two solutions and dilute so as to make 100 c¢.cm. Then add to the liquid thus obtained 1 gr. of chloral hydrate. If any free ammonia remains, gently warm in a water-bath to drive away the excess, or allow the alkali to volatilize by exposing the liquid to the open air. This solution lasts a long time without changing. M. Francotte also supplements Prof. Hoyer’s description of his process for obtaining carmine solution. t The latter directs chloral hydrate to be added to the neutral liquid to keep it, but does not state the quantity to be used. M. Francotte forms a carmine solution of 10 c.cm. by the addition of distilled water, to which is added 1 gr. of chloral hydrate. If a paste is required instead of a powder, Prof. Hoyer directs it to be made with alcohol, glycerine, and chloral, but does not give the quantities. M. Francotte uses to 1 gr. of carmine, 2 c.cm. of alcohol, 2 c.cm. of glycerine, and 1 gr. of chloral. Dry Injection-masses.—Prof. H. Fol writes that the red gelatine vermicelli mentioned at p. 312 (carmine emulsions) should be pressed out into slightly acidulated water (1 part acetic acid to 1000 parts water), The carmine will otherwise be washed out. _ Imbedding Diatoms.§—R. Hitchcock suggests a plan for imbed- ding diatoms from fresh gatherings. It is to prepare an artificial * Bull. Soc. Belg. Mier., x. (1884) pp. 75-7. t See this Journal, iii. (1883) p. 142. t Ibid., p. 141. § Amer. Mon. Micr. Journ., v. (1884) pp. 54-5. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 475 calcareous rock from a mixture of finely-ground lime and clay, making a kind of hydraulic cement, with which the diatoms may be mingled. When this hardens, the sections may be cut, and isolated by treatment with diluted hydrochloric acid. The large Pinnularia is a good species to begin with. Zentmayer’s New Centering Turn-table.*—The turn-table repre- sented in fig. 75 is the invention of Mr. J. Zentmayer. The plan of centering the slide is, it is claimed, quite original and perfect in its Fig. 75. results. The slide is placed so that its edges are in contact with the two pins projecting from the face of the plate. A ring with an oval inner edge is fitted to the periphery of the disk, in such a way that by turning it the slide is grasped at the diagonally opposite corners by the inner edge of the ring, and is thus centered longitudinally. The two pins centre it the other way. The ring may be easily removed, and spring clips substituted when desirable. Phosphorus Mounts.—It was recently stated t that diatoms mounted in phosphorus solution cannot be kept for any time. This is notso. Mr. J. W.Stephenson has slides mounted several years ago (one in 1873), which are as good now as at first. All that is necessary is to avoid long exposure to daylight which turns the diatoms an opaque red. Styrax.—On testing this medium (as supplied by Allen and Hanbury) with the refractometer, its refractive index is found to be 1-585 very nearly. It has so much colour that it is difficult to determine the third decimal with accuracy. If we take the index of diatomaceous silex to be 1°48, and of Canada balsam 1°52, it is seen that styrax gives a marked increase of visibility over balsam, for while balsam is only 9, styrax is more than 15. * Amer. Mon. Micr. Journ., v. (1884) p. 23 (1 fig.). + Engl. Mech., xxxix. (1884) p. 149. 476 SUMMARY OF CURRENT RESEARCHES RELATING TO A. C. Cole * considers gum-styrax to be a “perfect substitute for balsam,” that it “yields the best possible results,” and that it “may be considered absolutely permanent and unalterable.” The styrax solution is “even easier to work with than balsam, and air-bubbles are not produced in it by the application of heat.” Smith’s New Mounting Media.j—Prof. H. L. Smith has been experimenting with various substances to find satisfactory media of high refractive index for the mounting of diatoms, &c. The desiderata at which he has aimed are: Ist, high refractive index ; 2nd, a substance to be used in a fluid or semi-fluid state in the process of mounting ; 8rd, the property of hardening on the slide, so as to make a permanent mount; and, 4th, a proper cement, to protect it from decomposition if the material is in danger from that cause by reason of exposure to the air or to immersion fluids, Professor Smith is now assured that he has succeeded in his efforts, and has produced two media, both of combinations entirely new and heretofore unnoticed in chemistry. He has also devised a cement for rings upon the slides to protect the media, which is also new, and makes attractive mounts. His first medium is a transparent, colourless substance, in the form of a thick fluid, which hardens by heat applied in the same way as in mounting in balsam. The heat expels the fluid part of the mixture, and leaves a solid which is a permanent mount, and requiring no more care in subsequent handling or packing of slides than balsam. The index of refraction of this medium when solidified is 2-00. The second medium is a yellow-tinted, thick fluid, similar in handling to the last, and to be used and treated in the same manner, but having an index of 2°25 + when solidified. A perceptible brownish- yellow tint remains in this medium, similar to that of pretty old balsam which has been a little overheated. This medium would naturally be used for special examinations of particularly difficult objects, and the colour is not enough to be objectionable, though the first medium, with its absolute transparency, would be preferred for more common use. Used in a fluid state, the denser medium has scarcely any colour, but its refractive index is of course lowered a little. In either of them the resolution of Amphipleura pellucida is made with surprising ease and strength, and with light of very small obliquity compared with that which has been necessary in dry or balsam mounts. In short, it gives all the results which the high refractive index would lead us to expect, and with none of the objec- tions for cabinet use which belong to the solution of phosphorus and other mixtures. The cement for ringing is specially devised to avoid any danger of its attacking or decomposing the mounting medium. The following is a copy { of the report made to the State Micro- scopical Society of Illinois by a committee to whom were referred some slides of Diatomaceze mounted in the new media. * Methods of Micr. Research, Part x. (1884) p. lvii. + Amer. Mon. Micr. Journ., v. (1884) p. 71. t ‘The Microscope,’ iy. (1884) pp. 77-8. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 477 “ Your committee carefully examined the slides submitted to them, but gave special attention to the slides of Amphipleura pellucida mounted in a nearly white or colourless medium, whose refractive index is stated to be 2—. A new Bulloch Professional stand, with a 10-inch tube, was used. It was fitted with a condenser made on the Abbe pattern by Mr. Bulloch, the numerical aperture of which was stated by the maker to be 1-23. The condenser was used with a homogeneous-immersion fluid (cadmium chloride in glycerine). The illumination was furnished by a kerosine lamp with a flat wick turned edgewise toward the mirror, and the light was reflected through the condenser by the concave mirror. The objectives used were, first, a dry 1/6 of Bausch and Lomb, said to be of 140° air angle, with a Beck No. 3 eye-piece, which gives a supra-amplification of 13°88. The angle of light from the con- denser was as high as could be used by the objectives and fully illuminate the object, and with these appliances the lines showed with great distinctness. We then used a homogeneous- immersion Zeiss 1/18, 1:28 N.A., with the following eye-pieces: Beck No. 1, supra-amplification 5; Beck No. 2, supra-amplification 8°33; Tolles 1 in., supra-amplifica- tion 10; Beck No. 8, supra-amplification 13°88; Tolles 1/2 in., supra-amplification 20°83. The illumination was the same, except that the angle of light was as oblique as the condenser could give. With all of these eye-pieces the beads showed very strongly. The slide mounted in a yellowish medium with a refractive index said to be 2°3, did not seem to present any marked superiority over the other. Your committee would expect these media, particularly the colour- less one, to be of great value if they keep well. Their advantage in the study of diatoms is obvious. We would also expect them to be even more useful in histology if preparations can be transferred to them without injury. ‘They may also be of great service in the study of bacteria. By the process of staining, now necessary in the study of these structures, they are shrivelled and perhaps changed in other ways, and we may hope to learn much more about them than is now known if they can be studied in these media in a more natural condition.” (Signed by B. W. Thomas, Lester Curtis, H. A. Johnson, H. W. Fuller, and H. J. Detmers.) Wilks’s Cell—Mr. E. Ward supplies cells for mounting without pressure in Canada balsam made on a plan suggested by Mr. Wilks and shown in fig. 76. an a ea oes The cell is made of soft metal and, as will be seen from the figure, has four elevations alternating with depressions, the cover-glass 478 SUMMARY OF CURRENT RESEARCHES RELATING TO resting on the upper points of the curves. By leaving an excess of balsam round the cell and cover-glass, air-bubbles ultimately escape through the spaces, and loss by evaporation of essential oil in the balsam is provided for. If the cell is too deep for the object it can be pressed between two glass slips until shallow enough. Closing Glycerine Cells.—Mr. W. M. Bale writes: “I see by one or two remarks in the Journal that some manipulators still find a difficulty in securely closing glycerine cells. I have found the following plan obviate all liability to leakage. Use a cell of firm material, such as glass or ebonite, and a cover-glass of larger size, so that when in position it projects outside the cell for 1/12 in. or 1/8 in. all round. Fill the cell and press down the cover-glass, forcing out the superfluous glycerine; then (if on examination under the Microscope the object is found to be properly displayed) put on a spring clip to keep the cover close down, and with a fine syringe wash away the whole of the glycerine which may have exuded from the cell. The space below the projecting margin of the cover-glass will now be filled with water instead of glycerine, and by applying a piece of blotting-paper the water may be absorbed; the slide must then be allowed to stand for a minute or two till the outside of the cell is quite dry, when a little tenacious fluid cement may be applied at the margin of the cover, and allowed to fill the circular space outside the cell. Unless an excess of cement be placed on the slide there will be no tendency whatever to ‘run in, provided that the cell be quite flat, so that the cover can come into close contact with it all round, and that it be deep enough for the object. I formerly recommended this plan for mounting in fluids which would evaporate,* and I since find that it is equally applicable to a dense medium like glycerine, provided that the latter be syringed away from the outside of the cell, as directed. I have young Hippocampi preserved in ebonite cells in this manner, but I may add that it is not uncommon to find ebonite cells more or less bent, and such are useless for the purpose, it being essential that the cover should fit closely to the cell, as otherwise the water used in washing would enter it.” Getschmann’s Arranged Diatoms.—Whether diatoms ought or ought not to be “arranged” is a question which is more often answered in the negative, and in calling attention to the slides pre- pared by R. Getschmann of Berlin, we have no intention of objecting to the general verdict. We simply record the fact of the existence of the slides, and that they much surpass any of the previous efforts with which we are acquainted. With the diatoms are included Lepidoptera scales, Hchinoderm spines, &c. Classification of Slides.;—Dr. C. S. Minot suggests a scheme of arrangement of microscopical (and especially histological) slides based on embryology. The foundation of the system is primarily the germ-layers and then the order of development of the various organs. * See this Journal, iii. (1880) p. 864. + ‘Science Record,’ ii. (1884) p. 65. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 479 The first division embraces the ectoderm and its derivatives. Here would be placed in order the skin, nerves, glands, teeth, mem- branes, bones, and organs of sense, and all other organs derived from the outer germ-layer in as nearly as possible the order of their appearance in the embryo. To the second division belong the endodermal structures, the lining of the alimentary tract, the liver, respiratory organs of verte- brates, endostyle of Tunicates and the thyroid and thymus glands, pancreas, spleen, and stomach. The mesoblastic tissues may be divided into two great groups: the first, those of the mesenchyma, embraces the spicules of sponges and the skeleton of Echinoderms, smooth muscles, connective tissue, fat-cells, blood, blood-vessels, heart, lymphatics ; and, lastly, cartilage and bone. To the other division, to which the term mesothelial tissues may be applied, belong the peritoneum of the vertebrates and its homologues in other groups, striated muscle, and its modification, electric organs, the segmental organs of the lower forms, and the excretory organs of the higher forms, sexual organs, then the stomo- deum and its glands, and the proctodeum and its appendages. The position of the mouth of vertebrates and its accessories is uncertain, as doubts exist whether it is comparable to a portion of the stomodeum of the lower forms or is a superadded feature. In the case of compound organs the preparations should be placed with their most characteristic elements. Thus the liver should be placed with the hypoblastic tissues, the nerves and skin with the ectodermal, &c. In cases of series of sections of one animal, they of course should be kept together. Dr. Dimmock adopts a different plan. Hach of his slides is numbered in the order of preparation, and then two card catalogues are made, one by organs, the other systematic, each card referring by a number to the corresponding slide. On these cards can be entered full accounts of the specimen, its mode of preparation, the special features presented, &c., and thus with a slight additional amount of labour, the advantages of each system of arrangement may be obtained. Blackham’s Object-Boxes.*— Dr. G. E. Blackham takes the common rack-boxes for twenty-four slides, and putting on the cover, pastes a piece of stout twilled muslin on the back and lapping over on to the cover. This forms a hinge, and gives the boxes a uniform look. Each box is devoted to a special series or class of objects, and properly labelled, and stands up on end in a revolving book-case. The slides le flat, and the whole collection is in reach from the working table, without getting out of the chair. For indexing each box Dr. Blackham, with an electric pen, makes a label covering the inner side of the cover, the name of each slide is written on this, on the line opposite the slide itself as it stands in the box. These boxes are cheap, convenient and portable, and are, he considers, preferable to the more elaborate and costly cabinets of drawers. * Proc. Amer. Soc. Micr., 6th Ann. Meeting, 1883, pp. 236-7. - 480 SUMMARY OF CURRENT RESEARCHES RELATING TO Stillson’s Object Cabinet.*—Dr. J. O. Stillson’s cabinet consists of a number of trays made of thick pasteboard. They are 9 in. wide and 16 in. long. ‘There are two rows of slides in each tray and 10 or 12 in each row according to the partitions, which can be removed or left in. The depth of the tray is equal to the thickness of the thickest slides, so that when they are in place, each lying flat, they fill the apartment. ‘There is a lid to each tray, also made of paste- board but stiffened, and made heavier by the addition of a strip of wood, such as is used in making cigar boxes. This strip extends all around the margin of the lid, and there is another across the middle the long way. Two long openings are cut through the lid, about 2 in. wide, so that when the lid is closed it will press the slides down in their places firmly, but at the same time not touch the cover-glasses. High, dry and opaque mounts can be placed alongside of the thinnest balsam or diatoms, and when it is desired to look for a slide the whole tray can be surveyed with the eye at a glance, and the names of twenty or twenty-four specimens can be read without opening the tray. When the trays are all in the box, the lid holds them firmly in place suit- able for shipping. He has borders for the labels printed on fancy coloured paper, and writes in pencil on the wrong side of the label such a history as he desires and pastes it on the slide. Then the name labels are cut with a circular No. 8 punch, and pasted on the border paper. ‘There is plenty of room to write in front the English and Latin names, date and number; by turning the slide round one can read from the back through the glass the history and mode of preparation. Pillsbury’s (or Bradley’s) and Cole’s Mailing Cases. — This “mailing case,” the design of J. H. Pillsbury, is intended to supply a demand for some safe and cheap means of packing one or more slides for sending through the post. The entire device comprises three differently shaped pieces of wood (tops, bottoms, and centres) so formed that two, three, or more may be put together as shown in Fig. 78. Tm ee rn rN fig. 77. For one slide the top and bottom pieces are used, for two slides the centre pieces also, and so on to any convenient number. The cross section fig. 78 shows the relation of the parts of the case to the slide. The pinching of the wooden lips on the margin * Proc. Amer. Soc. Micr., 6th Ann. Meeting, 1883. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 481 of the glass outside the mounting serves to hold the slide securely in place, and to protect the mounting from possible injury. Every dozen tops and bottoms is accompanied with twenty-four strips of gummed paper which Fic. 79. may be used on the edges to secure the pieces before wrapping for mailing. If one slide is to be sent the strips may be gummed lengthwise on the edges. If centres are used for more slides the strips may be used to pass around on to top and bottom. The slight shrinking of the moistened paper in drying pinches the slide sufficiently to hold it securely. A. C. Cole uses the boxes shown in fig. 79. They consist of a piece of wood 3} in. x 1 in. and 1/2 in. thick in which a coarse saw- cut has been made nearly through it as shown in the figure. The slide is placed in the groove thus formed with a little cotton wool and the open side is filled up with a strip of wood about 3/16 in. section. Apams, J. M.—How to keep [send] living Infusoria. [Dr. A. C. Stokes uses Lemna plants which keep the water sweet and supply oxygen while in transit. | The Microscope, IV. (1884) p. 64. B., W.—Microscopical. [Mounting Cuticle of Leaf.] Engl. Mech., XX XIX. (1884) p. 132. BrEHRENs, W.—See Boecker, W. E. Buiocumann, F.—Ueber Einbettungsmethoden. (On imbedding methods.) [ Post.] Zeitschr. f. Wiss. Mikr., I. (1884) pp. 218-33 (2 figs.). Borcxer, W. H.—Ueber ein neues Mikrotom mit Gefriereinrichtung, automa- tischer Messerfuhrung und selbstthatiger Hebung des Objectes. (On a new Microtome with freezing apparatus, automatic knife-guide, and automatic raising of the object). [Post.] Zeitschr. f. Instrumentenk., LV. (1884) pp. 125-7 (2 figs.). Zeitschr. f. Wiss. Mikr., I. (1884) pp. 244-8 (by W. Behrens). Boorn, M. A.—Mailing packages of Diatoms. (Inquiring how to send small exchanges to foreign countries. ] Amer, Mon. Micr. Journ., V. (1884) p. 100. Born, G.—Die Plattenmodellirmethode. (The method of modelling by [wax] plates.) [Post.] Arch. f. Mikr. Anat., X X11. (1883) pp. 584-99. Amer, Natural., XVIII. (1884) pp. 446-8. BucuKa, K.—Ueber Hematoxylin und Brasilin. (On Hematoxylin and Brasilin.) Nachr. K. Gesell. Wiss. Gottingen, 1883, pp. 60-66. Buoxton, G. B.—Monograph of the British Aphides. Vol. iv. ix. and 228 pp. (27 pls.). 8vo, London, 1883. [Contains “ The preservation and mounting of Aphides for the Microscope,” “The preservation of Aphides for the Museum,” and “ The dissection of Aphides.” Supra, p. 466.] Burrill’s (T. J.) Stainiag fluid, directions for use of. Micr. Bulletin, I. (1884) pp. 21-2. CatTanEo, G.—Fissazione, Colorazione e Conservazione degli Infusorii. (Fixing, colouring, and preserving Infusoria.) Concld. Bollett. Scientif., V. (1883) pp. 122-8. Cleaning Slides and Covers—Letter by J. C. Lathrop. [See also ante, p. 323.] Amer. Mon. Micr. Journ., VY. (1884) p. 79. Coat, R. D.—Preparation of the Ethyl] Ether of Gallic Acid. (Cf. III. (1883) p. 931.] Amer, Mon, Micr. Journ., V. (1884) p. 82. Ser, 2.—Vot. TV. DE 482 SUMMARY OF CURRENT RESEARCHES RELATING TO Coir, A. C.—Studies in Microscopical Science. Vol. II. No. 15. Sec. I. No. 8. Adipose Tissue, pp. 29-32. Plate 8 x 250. No. 16. Sec. II. No. 8. pp. 29-34. Epidermal Tissue. Plate 8. T.S. of aérial root of Dendrobium x 130. No. 17. Sec. I. No.9. Development of Bone, pp. 33-6. Plate 9. Ossi- fication of Cartilage (Quain) x 300. No. 18. See. II. No. 9. pp. 35-8. Vasicular Tissue. Plate 9. Bast, Sieve Tubes and Liber Cells. 5 a Methods of Microscopical Research. Part IX. pp. xlix.lii. Mounting (continued). Description of Materials. Part X. pp. liii—vii. Mounting (continued). The Preparation of Diatom- aces. Popular Microscopical Studies. No. VII. A Grain of Wheat (con- "cluded), pp. 25-8.—The Common Bulrush (Typha), pp. 29-31. Plate 7. T.S. of Stem, double stained, x 75. No. VIII. The Intestine, pp. 338-7. Plate 8. T. 8. eum of Cat injected x 90. Collins’ (C.) Series of 48 Fish Scales. Micr. News, TV. (1884) p. 109. Cornit, —.—Sur le mode de conservation des pices anatomiques destinées étre examinées au Microscope. (On the mode of preserving anatomical objects required to be examined with the Microscope. [Brief note only of original paper. The best preserving liquid is 90 per cent. alcohol using a volume at least 20 times as great as that of the piece to be preserved, which should if possible be reduced to 1/2-1 em. cube.] Journ. de Micr., VIII. (1884) p. 189, from Progrés Medical. Cox, J. D.—[Prof. H. L. Smith’s] New Mounting Media. [Supra, p. 476.] Amer. Mon. Mier. Journ., V. (1884) p- 71. CozE and Simon, P.—Recherches de pathologie et de thérapeutique experimen- tales sur la Tuberculose. (Experimental pathological and therapeutical observations on Tuberculosis. ) [Contains I. Technique. | Journ. de Microgr., VIII. (1884) pp. 235-9, from Bull. Gén. de Thérapeutique. Creesz, BE. J. E.—An inexpensive Turn-table. [A home-made turn-table which any one with ordinary knack can make for himself at the cost of a shilling.”’ Journ. of Micr., III. (1884) pp. 106-7 (8 figs.). Desy, J.—Notes diatomiques. (Notes on Diatoms). [I. On MM. Prinz and Van Ermengem’s work on the structure of the valves of diatoms (post). II. Discovery of Zerpsinoé musica in Spain. III. Special slides of diatoms by Moller (post).] Journ. de Microgr., VIII. (1884) pp. 228-31. Dirret, L.—Die Anwendung des polarisirten Lichtes in der Pflanzenhistologie. (The use of polarized light in vegetable histology.) [Post.] Zeitschr. f. Wiss. Mikr., I. (1884) pp. 210-7 ( figs.). 3 » Kalium-Quecksilberjodid als Quellungsmittel. (Biniodide of mercury and potassium as a swelling agent.) [ Post. Zeitschr. f. Wiss. Mikr., I. (1884) pp. 251-3. Dourxesz, R. P. H.—Mounting in balsam in cells. [Post.] Amer. Mon. Micr. Journ., V. (1884) pp. 84-85. Epinecrr, L.—Nctiz, betreffend die Behandlung von Pripar aten des Central- nervensystems, welche zur Projection mit ‘dem Scioptikon dienen sollen. (Note on the treatment of preparations of the central nerve-system intended for projection with the Sciopticon.) _[ Post.] Zeitschr. f. Wiss. Mikr., I. (1884) pp. 250-1. Etsner, F.—Mikroskopische Atlas. Hin illustrirtes Sammelwerk zum Gebrauche fiir Gesundheitsbeamte, Apotheker, Drogisten, Kaufleute und Gebildete Laien. (Microscopical Atlas. An illustrated compendium for the use of officers of health, spoineeani druggists, merchants, and well-informed lay- men.) Part I. 9 pp. and 2 pls. of 27 photomicrographs. 4to, Halle, 1884. [Contains Coffee and Coffee-surrogate. Tea and Tea-surrogate. | ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 483 Ferevus, 8. T.—Double staining sections of Buds. Micr. Bull., I. (1884) p. 18. Fresco, M.—Notiz iiber die Anwendung des Farbstoffes des Rothkols in der Histologie. (Note on the use of the colouring matter of the red cabbage in Histology.) [Post.] Zeitschr. f. Wiss. Mikr., I. (1884) p. 253-4. FRENZEL, J.—Ueber die Mitteldarmdriise der Crustaceen. [Contains “Methods of studying the so-called liver of the Crustacea.” Amer. Natura!., XVIII. (1884) p. 556-7. Post.) MT. Zool. Stat. Neapel, V. (1884) p. 51. Gace, 8S. H.—Notes on the use of the Freezing Microtome. [Post.] Science Record, II. (1884) pp. 134-5. Gittay, E.—L’Heématoxyline comme réactif spécifique des membranes cellu- losiques non lignifiées et non subérifiées. (Hematoxylin as a reagent for non-lignified and non-suberose cellulose membranes.) _[ Post. Arch, Néerl. Sci. Exact. et Nat., XVIII. (1883) pp. 437-52. Grant, F.—Microscopic Mounting. IX. Mounting Media. 1. Phosphorus and monobromide. 2. Advantages as to the absence of contraction and as to visibility. 3. Thin aqueous fluids. 4. Advantages of different media with respect to granulation. 5. Thick aqueous media: advantages as to staining and pressure. (See. II. requires considerable correction. nter alia, the refractive index of diatoms is put at ‘‘about 1:5,” and balsam at 1-528, or a visibility of °028! Diatoms are stated to be more visible in air than in phosphorus. The disadvantages of air-mounting are not referred to its inapplicability for fine markings, but to a “ dulness or mist which gathers inside,” &c. Engl. Mech.. XX XIX. (1884) pp. 148-50. Gravis, A.—Procédés techniques usités & la Station Zoologique de Naples en 1883. (Technical methods used at the Naples Zoological Station in 1883.) [Summary of various methods previously published, and post. Bull. Soc. Belg. Micr., X. (1884) pp. 104-27, 132-3. Haacxr, W.—Entwasserungsapparate fiir Macro- und Microscopische Prapara- tion. (Dehydrating Apparatus for Macroscopic and Microscopic Preparations.) [ Post. ] Zool. Anzeig., VII. (1884) pp. 252-6 (1 fig.). HartzeLy.—A method of staining the Bacillus [of tubercle.] [Post.] Amer. Mon. Micr. Journ., V. (1884) p. 76-7, from Medical Times. Ha ziewoop, F'. T.—Blue Staining. [The stain—described III. (1883) p. 733—“ gives surprisingly fine results with micrococci, bacteria, bacilli, &e.” Method of suspending the slides in the water. ] Amer. Mon. Mier. Journ., V. (1884) pp. 83-4. Herrzmann, C.—Mikroskopische Morphologie des Thierkérpers im gesunden und kranken Zustande. (Microscopical morphology of the animal body in health and disease.) xvi. and 876 pp. (880 figs.). S8vo, Wien, 1883. Also 8vo, New York, 1884. Hitcucock, R.—Styrax and Liquidambar as substitutes for Canada Balsam. [Recommendation of Styrax. ] Amer, Mon. Micr. Journ., V. (1884) pp. 69-71. 5 », Crystals of Arsenic. [Select a small tube about 1 in. in length, and fit it in a holder made of a thin strip of copper, brass, or other metal having a hole bored through it to receive the tube. Let the mouth of the tube project slightly above the metal, and support the latter in some convenient way over a spirit lamp. Place asmall quantity of white arsenic in the tube, and apply heat slowly until a white powder begins to collect about the mouth. Then warm a glass slip, and hold it over the top of the tube until bright crystalline par- ticles appear on its under surface. Then remove the lamp and let the tube cool. ] Amer. Mon. Micr, Journ., V. (1884) p. 71-2. 3 », Cleaning Polycystina. ,, p 5 pp. 72-3. 2 Ke 2 484 SUMMARY OF CURRENT RESEARCHES RELATING TO Hircucock, R.—Microscopical Technic. III, IV. Mounting Objects Dry. Amer, Mon. Micr. Journ., V. (1884) pp. 73-4, 91-4. 3 » Spring Collections. ae cp % 9 pp. 77-8. Horunet, F. v.—Ueber eine Methode zur raschen Herstellung von brauchbaren Schliffpraparaten von harten organisirten Objecten. (Ona method for the rapid preparation of useful sections of hard organized objects.) [Post.] Zeitschr. f. Wiss. Mikr., 1. (1884) pp. 234-7. HorrmMann, F. W.—Einfacher Einbettungsapparat. (Simple imbedding appa- ratus.) [Post.] Zool. Anzeig., VII. (1884) pp. 230-2 (1 fig.). Houzner, G.—Zur Geschichte der Tinctionen. (On the history of Staining.) {Post.] Zeitschr. f. Wiss. Mikr., I. (1884) pp. 254-6. JACKSON, E. E.—How to Mount Casis. [After allowing urine to settle, pour off and wash sediment repeatedly with clean water, the object being to get rid of the albumen. The white sediment consists of casts and epithelia. Have ready a solution of eosin, 5 ers. to 1 oz. (water 3, alcohol 1), pour it on sediment, allow to stand 30 minutes, then wash repeatedly as long as colour comes freely. Allow to settle, place a drop on cover, when dry enough to adhere, rinse off with alcohol to get rid of water; dry. Wet with spirits of turpentine and mount as usual in balsam. ] The Microscope, TV. (1884) pp. 78-9. x x Mounting Desmids. [A dip was put in a cell, the water absorbed by blotting-paper, then a drop of mixture of carbolated mucilage of gum arabic and solution of borax was put on the desmids and they were covered and ringed. It remains to be seen whether the medium has bleaching or shrinking properties. ] The Microscope, LV. (1884) p. 117. Kinestey, J. S.—Microscopical Methods. II. [Elementary instruction. ] Science Record, II. (1884) pp. 124-7. L., V. A.—To Harden Animal Tissues. Sci.-Gossip, 1884, p. 89. Lacrruzm, G.—Hine Praparirmethode fiir trockene mikroskopische Pflanzen. (A method for preparing dried microscopical plants.) [Post.] Bot. Centralbl., XVIII. (1884) pp. 183-4. Laturop, J. C.—See Cleaning. Linpt, O.—Ueber den mikrochemischen Nachweis von Brucin und Strychnin. (On the microchemical analysis of Brucine and Strychnine.) Zeitschr. f. Wiss. Wikr., 1. (1884) pp. 237-40. Meyer, H. V.i—Fermere Mittheilung tiber die Kleisterinjection. (Further com- munication on paste injection.) [Further experience of his modification of Pansch’s method has proved its value. Remarks on the use of fuchsin and vermilion.]} Arch. f. Anat. u. Physiol.—Anat. Abtheil., 1883, pp. 277-8. Micuart, A. D.—British Oribatide. Vol. i. xi. and 336 pp. (31 pls.). 8vo, _ London, 1884. [Contains description of cells used for observing the development and im- mature stages, pp. 68-70 (glass rings made from thinnish 3/4 or 7/8 in. tubing and 3/8 in. deep). Collecting and preservation, pp. 99-109. Draw- ing, pp. 191-5. LPost.} Moe.ter, J—Das neue Patent-Schlittenmikrotom von C. Reichert. (The new patent sliding Microtome of C. Reichert.) [Post.] Zeitschr. f. Wiss. Mikr., I. (1884) pp. 241-4 (1 fig.). Pim, G.—Cell-sap Crystals. [Supra, p. 470.] Journ, of Bot., XXII. (1884) p. 124. Pray, T., junr.—Cotton-fibre and its structure. (Refers to the “importance of examining cotton by the Microscope,” and _ the “ advantages which manufacturing corporations would gain by select- ing their stock in this way.”] Science, IIT. (1884) p. 583 (Proc. Soc. of Arts. Mass. Inst. of Technol., April 10). Ratagpouu, J.—Les Diatomées. Reécolte et préparation. (The Diatomacee. Collection and preparation. Contd.) Journ. de Microgr., VIII. (1884) pp. 115, 173-6, 231-4. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 485 RINDFLEIScH.—Bacilli of Tubercle. [They are best stained by fuchsin, soluble in alcohol but not in water. Two or three drops of a concentrated solution in 2-3 cm. of anilin-oil water are sufficient. The staining is especially good at 40° C. The bacilli are uniformly stained if a few drops of fuchsin ere added toa mixture of equal parts of alcohol, water, and nitric acid. ] The Microscope, 1V. (1884) p. 91. Suarp, B.—On Semper’s method of making dried preparations. [Post.] Proc. Acad. Nat. Sci. Philad., 1884, pp. 24-7. Suarp, H.—On the Mounting of Objects in cells with Canada Balsam medium. Journ. Koy. Soc. N.S. Wales, XVI. (1883 for 1882) pp. 286-8. Sruon, P.—See Coze. Sack, H. J.—Pleasant Hours with the Microscope. [Spiral vessels of rhubarb, &e.—Oxalate of Lime in Wood Sorrel] [Fish scales] [Proboscis of Ophideres] [ Wings of Insects]. Knowledge, V. (1884) pp. 240, 282-3 (8 figs.), 330-1 (2 figs.), 371-2 (1 fig.). SmitH’s (H. L.) New Mounting Medium. [Svpra, p. 476.] [See also Cox, J. D.] The Microscope, IV. (1884) pp. 77-8. Amer. Mon. Micr. Journ., V. (1884) p. 80. StoweLi, C. H.—Studies in Histology. Lesson I. Injecting. II. Hardening, Softening, Dissociating and Normal Fluids. The Microscope, IV. (1884) pp. 49-56, 80-6. a A The Measurement of Blood-corpuscles. [Discussion of recent articles. He considers the relative size of the red blood-corpuscles as given by Gulliver incorrect. ] The Microscope, LY. (1884) pp. 60-1. a 3 White Zine Cement. {Commendation of it when properly put on, in opposition to R. Hitchcock’s view that it will run in and spoil the mounts. | The Microscope, 1V. (1884) p. 62. Walmsley & Co.’s Circular on Bacillus Staining. [Vol. III. (1883) p. 310.] The Microscope, 1V. (1884) pp. 79-80. West, T.—Naphthaline. [‘‘It is considered by Prof. Williamson of Manchester, to furnish the very best of all substances for imbedding delicate microscopic subjects in previous to cutting sections.” Journ. of Microscopy, III. (1884) pp. 113-4. See also p. 119. WILLs, —.—Mounting Desmidiee. [Plain water—gold size.] Proc. Manch. Lit. and Phil. Soc., XXI¥. (1882) pp. 38-40. Witson, C. B.—The mesenterial filaments of the Alcyonaria. [Contains ‘‘ Methods of preparing the Alcyonaria.” Amer. Nat., XVIII. (1884) p. 558. Post.] UT. Zool. Stat. Neapel, V. (1884) p. 3. ( 486 ) PROCEEDINGS OF THE SOCIETY. Mertine or 9TH Aprit, 1884, ar Kine’s Cottzer, Srranp, W.C. THE Presipent (THE Rey. W. H. Dawiinerr, F.R.S.) In THE Caarr. The Minutes of the meeting of 12th March last were read and confirmed, and were signed by the President. The List of Donations (exclusive of exchanges and reprints) re- ceived since the last meeting was submitted, and the thanks of the Society given to the donors. From Hinde, G. J.—Catalogue of the Fossil Sponges in the Geological Department of the British Museum Oe etistory 248 pp. and 38 pls. 4to, ree 1883... .. The Trustees. Mickoscone by Chevalier... .. Mr. W. Forgan. Martin, B.—System of Optics. xxiv. and 295 PP. 3 xxxiy, ls, 8vo, London, 1740 .. é : Ditto. Collection of Australian Reptiles and Amphibia: Sty elon r. W. H. Pickels. Portrait of H. J. Slack, Esq... .. Recta Fa Mr, Slack. The President said that since their last meeting they had received an intimation from the R. Accademia dei Lincei of Rome, of the death of Signor Quintino Sella, who as President of the Academy was one of their ex-officio Fellows. He proposed that a vote of con- dolence should be forwarded to the Academy expressing the sympathy of the Society with the Academy in the loss of their illustrious President. Dr. Anthony having seconded the proposal, it was carried unanimously. The President proposed that as they were favoured by the presence of Dr. Carpenter, who intended to deal with the subject of binocular vision in the Microscope, the other business on the agenda should be postponed. This was approved by acclamation. Dr. Carpenter then addressed the meeting “On the Physiology of Binocular Vision with the Microscope,” illustrating the subject by some large photographs, drawings on the black-board, &c. He said :— The reason of my venturing to offer to the Society the views which I entertain upon the subject specified as the title of this communi- cation, is that in the last number of the ‘ Journal’ of the Royal Micro- scopical Society, at the end of a paper by Prof. Abbe, a doctrine is put forward on the nature of Stereoscopic vision with the Microscope, which appears to me to be inconsistent with our knowledge of the physiology, and also with our experimental knowledge of the pheno- 2 PROCEEDINGS OF THE SOCIETY. 487 mena, of stereoscopic vision. It is not, I think, so much a question of optics, as of the physiology of vision. If it was one of optics, I should certainly not venture to put myself in antagonism with one who is probably the greatest living master of the theory of the Microscope. But I think I shall be able to show that it is essentially a question of physiology, and in part also of psychology. Ever since Wheatstone’s invention of the Stereoscope, something like fifty years ago, I have had the subject constantly before me: and from the first introduction of the binocular Microscope, I have used it continually -for objects of suitable character. So completely, indeed, am I accustomed to it, that when I look at some of the same objects under the monocular Microscope, I scarcely know them again. The manner in which we form our visual conceptions from im- pressions produced upon the retina, is a matter of both physiology and psychology, lying on the border line between the two. Our visual conceptions are formed by the process which is known as “ suggestion ” ; that is, they do not necessarily conform to the visual impressions produced upon the retina, but they are suggested to us by these visual impressions; and it sometimes occurs that our conceptions are erroneous. All who have given attention to the physiology of vision, agree in considering our ordinary interpretations of the solidity of an object placed before us, to be dependent upon a mental co-ordination of our visual and tactile sensations. A child moves its hands towards an object presented to its vision, and educates itself to a conception of its form by the conjoint use of its sight and its touch. It has happened that in some cases persons have obtained sight for the first time, having been born blind, at an age when they have been able to record their impressions of objects presented to their sight, and to manifest their difficulties of interpretation. Many years ago I had the opportunity of observing a child three years old, who had been operated on for congenital cataract. He was too young to describe his impressions to us, but we could observe when he was guided by sight and when by touch, and it was very interesting to watch him under these circumstances. In the lodging where he was staying whilst under treatment, everything about him was strange, and he used his sight and his touch conjointly in familiarizing himself with them until he had learned to correlate the two impressions. But when taken to his own home where the surroundings were per- fectly familiar to him, he was for some time entirely guided by touch ; he seemed to be quite puzzled by the sight of them, and often shut his eyes in order to understand where he was. Many of you have heard of the case recorded by the celebrated Cheselden, the subject of which, being much older, could describe his own sensations. For a long time after he could see distinctly, he could not distinguish solid objects by vision alone from flat pictures. Not very many years ago, the case was published of a young woman who from birth had possessed enough sight to enable her to distinguish light from darkness, but who could not see the form of any object about her. She had been accustomed to work with her needle; and her thread, needle, scissors, balls of cotton, &c., were all perfectly well known to 488 PROCEEDINGS OF THE SOCIETY. her by touch. You would suppose that the peculiar form of a pair of scissors, as suggested to the mind through the medium of touch, would be recognized through the sight more readily than anything else; and yet when it was first shown to her, she utterly failed to recognize it as the implement which she had been in the habit of handling. This recognition of a solid form from a visual picture, then, is the result of the experience we gain in very early life, from the association of the mental impressions made by the retinal pictures with those we obtain through the sense of touch,—by which I mean not only the contact with the fingers, but the muscular action which gives movement to them,—so that, in course of time, the visual picture comes to suggest the solid form of the object to the mind. Our best evidence of this is derived from pictures obtained by means of photo- graphy ; especially those in which the relations of light and shade are strongly brought out; for these pictures suggest the idea of solidity much more perfectly than any others can do. Some of you will pro- bably remember the old Dioramic pictures in the Regent’s Park, with their wonderful appearance of solidity, especially in the case of archi- tectural designs; the impression produced being so entirely that of solidity, that it was only by moving the head from side to side that the illusion was detected. These pictures were based on photographs ; Daguerre and others having worked out the original “daguerreotype ” process for the purpose of producing them most effectively. In ordinary drawing and painting, an artist is subject to continual changes in the conditions of the light and shade, even in the course of half an hour; and therefore no painting, except one by artificial light, can give a true representation of light and shade at any par- ticular moment. Therefore it is that photographs of many subjects are most wonderfully illusive, and most especially so when they are looked at with only one eye. 'The explanation of this effect is, that when you look at the picture with both eyes, and it is tolerably near to you, you are forced to see it as a flat surface; but when you shut one eye and keep the head still, you lose the power of measuring relative distances; and a visual conception of solid form is suggested by its chiaroscuro and its perspective. If you look, for example, with one eye at the photographs of relievos hanging upon the opposite wall, you will, if you have not tried the experiment before, be astonished at the way in which the figures seem to stand out with all the effect of stereoscopic relief. This is a pure case of mental suggestion ; and is due to the perfect similarity of the photcgraph to the retinal picture produced by natural vision of the object itself upon a single eye. The camera, like the eye, projects a flat picture, which is recorded by photography; and you have then permanently just the picture which one eye would form of the object. You look at this with one eye, and, trained by experience, you interpret what you see according to your preconceived conceptions. A similar effect is obtained when you look at such pictures with both eyes, at a distance great enough for the axes of the eyes to be virtually parallel. I remember some large imitation relievos on the cornices of some of the apartments in the Louvre at Paris, and some still larger pic- PROCEEDINGS OF THE SOCIETY. 489 tures of the same kind in the Bourse, by which the impression of solidity is so well given, that, though the paintings are quite flat, they are generally taken by strangers for real relievos. I have a photo- graph of a figure in such low relief, that, looking at it with both eyes at a distance of only two feet, you could almost swear to its solidity; the suggestion of solidity given by its lights and shadows being so vivid, as to overcome the corrective effect of the binocular perception of its flatness. I dwell upon this point, because it underlies the whole inquiry before us. I have here four large photographs of plaques repre- senting the Four Seasons, with the ornamentation and figures in high relief. When you look at three of these with one eye, you will scarcely be able to persuade yourselves that you are not seeing actual relievos, so vividly do the figures stand out. But I have hung one of them upside down; and though you may not all see it as I do, I think the impression upon most persons will be that the figures are hollowed out, instead of raised. In each case the illusion depends mainly upon the light; and it is most complete when there is but one source of light in the room, corresponding with the lights in the photograph. The mental impression is entirely due to suggestion; you know the position of the light, and can tell in which direction the shadows would Fic. 80. fall; and when the shadow is made to fall as it would if the object were hollow, then the mind interprets the object as such. Another remarkable instance of suggestion is afforded by this figure of a rhomb (fig. 80), which, as you look at it, may seem to change from one position to another, some- times appearing to stand upon its narrow side, at other times to be lying on its broad side. Sir D. Brewster says that the perception changes from one to the other, as you feel your mind changing ; but I believe that the perceptional and therefore the mental change is the result of the wandering cf the eye from the point a to the point b; for I have never failed to see one or the other aspect, by making my eyes converge upon one or the other of these two points, which then becomes the salient angle. This is a case in which two different effects of projection may be produced by the same visual impression; a consideration much dwelt upon by Sir Charles Wheatstone in his original memoir,* as proving that the conception of solid form is visually suggested to the mind, not a mere optical effect. I now come to the subject of Binocular Stereoscopic vision, which was first elucidated in that memoir. Painters had long been aware of the fact, that if you look at a near object with both eyes, you form different pictures with your two eyes. How is it, then, that we are not * “On some remarkable and hitherto unobserved phenomena of Binocular Vision.” Phil. Trans., 1838, pp. 371-94. 490 PROCEEDINGS OF THE SOCIETY. puzzled by these different pictures, presented to the mind at the same time ? Wheatstone applied himself to the study of this question; and in the course of his investigations it occurred to him that the dissimi- larity of the two pictures was really the cause of the sense of pro- jection ; and that though we have this sense with a single eye, it is in such case by no means so unmistakable. He therefore reasoned in this way ; if you draw two pictures of an object, one as it appears to the right eye, and the other as it appears to the left, and then throw the images of these dissimilar pictures upon the two eyes respectively, you will get a solid effect. The original form of the Stereoscope was a reflecting apparatus, consisting of two mirrors placed together at a right angle, so that each reflected the image of its own picture direct to its own eye; and with this instrument Wheatstone found that two mere outlines of a solid, drawn as already described, and reflected so that each was seen only by the eye for which it was drawn, resulted in the production of a perfect perception of the solid form. No one welcomed this discovery more than Sir David Brewster; who said that it was the greatest that had been made in vision since the time of Newton. This combination of two dissimilar pictures is the funda- mental principle of the Stereoscope. In the form of that instrument now familiar to you all, a pair of small photographic pictures, taken in different perspectives, are brought one before the right eye, the other before the left, by two halves of a double-convex lens placed back to back, so as to act both as prisms and as magnifiers. The points of view from which the two pictures are taken, are generally, I believe, about 15° apart ; that being the usual angle of convergence of the axes of the eyes at the ordinary reading distance. The late Mr. Claudet, who paid a great deal of attention to this subject in relation to portraiture, tried various angles ; and having taken pictures at 5°, at 10°, at 12°, at 15°, and at 20°, he found that 5° gave very little projection, 10° was more satisfactory, but 12° was much better ; and for people with nearly approximated eyes it was found to be sufficient; but for most people, 15° was required to bring out the full stereoscopic effect, whilst if he widened the angle to 20° all the pro- jecting parts came out with ludicrous exaggeration. (I have an early stereoscopic photograph of an equestrian statue of Napoleon, showing this exaggeration in a very marked degree, the two pictures having been taken at too wide an angle.) Asan illustration, take a truncated pyramid which is placed end-on before one eye, as is shown in fig. 81a; with that eye alone you would be unable to measure the relative distances of its parts, and the borders of its base and truncated top would appear like two squares symmetrically placed one within the other. But if placed in front of the nose, the right eye would see more of the right side of the pyramid (as in the fig. 81 ¢), whilst the left eye will at the same time see more of the left side of it (as in fig. 816); and if these two pictures are put into the Stereoscope, and each is seen at the same time —the one by the right eye, and the other by the left—the apparent solidity of the figure is brought out perfectly ; that is, these two dis- similar pictures, viewed simultaneously, suggest to the mind a con- PROCEEDINGS OF THE SOCIETY. | 491 ception of the projection of the solid from which they are taken. But if the figure, instead of being solid, was hollow, and was placed before the eyes so as to show its interior, then the right eye would see more of the left side, and the left eye would see more of the right side (as in figs. 81 e and 81d); and when these two pictures are put into the Stereoscope, the centre appears to recede in an unmistakable manner. Ihave here a stereoscopic slide showing these two pairs of pictures at the same time; and if you look at it in the Stereoscope, the “conversion of relief” produced by the “ crossing” of the right and the left hand pictures of the pyramid, will be at once apparent. But in addition to these impressions of solid form, another very curious fact now comes out. The four small squares are of exactly the same size in the pictures; and yet as you look at them in the Stereoscope, you will all say that the square at the end of the hollow pyramid seems larger than the other. The apparent excess differs in different persons; for some see the receding pyramid as if much deeper than others, and describe it as like a tunnel; and to them the small square looks very much larger. This is another case of mental suggestion, and one which no optical diagrams can explain, because it is clear that the retinal pictures must be of exactly the same size, however different they may seem visually. Sir Charles Wheatstone in his second Memoir (Phil. Trans., 1852) clearly proved, by experiments made with his improved reflecting Stereoscope, that our conception of the size of an object pictured on the retina ordinarily depends on our appreciation of its distance; and that this again (in the case of a near object), depends upon the convergence of our optic axes. If we have an object of known size, and we bring it nearer to the eye, it does not seem to be a larger object: because we know that though it subtends a wider visual angle, making the retinal picture larger, its distance from us has diminished. And he showed that by making the optic axes converge, and so suggesting to the mind that the object was approaching, though it was not brought 492, PROCEEDINGS OF THE SOCIETY. nearer (its retinal picture remaining of the same size)—it seemed to become smaller; while, by opening out the angle of convergence, the pictures seemed to grow larger. Here, then, we have a most perfect example of an automatic mental interpretation, in which the apparent size is determined by the conjoint impressions we are receiving from the convergence of the optic axes and the actual size of the retinal pictures. And so when the mental interpretation of the stereoscopic form throws the small square back, and the visual picture remains of the same size, the fact of its receding without diminishing suggests the mental impression that it is of a really larger size. ‘There is no gainsaying these things; they are simply facts in Mental Physiology ; and, as I have already said, they are not a matter of Optics, but the results of a mental process of interpretation of the visual impressions received. I might go on to demonstrate this still further by means of the Pseudoscope, if time permitted. This is an arrangement of prisms for bringing the right-hand picture of an actual object to the left eye, and the left-hand picture to the right eye ; and just as the “‘ crossing” of two stereoscopic pictures produces a conversion of relief in the com- posite image, so does this reversal of the combination suggest to the mind a reversal of the relief of the image of the actual object. The effect of ‘suggestion ” is well shown by a simple experiment. Here is an ordinary tin cake-mould ; now if you place this before one eye so that the light falls directly into it, and you look at it with that eye alone, inasmuch as you are more accustomed to see the solid form than the hollow, you will probably see it projecting towards you. (To see it in this way, there must be no shadow, for this will oblige you to recognize its concavity.) The experiment is best made by daylight, the mould being held up soas to face the person looking into it with his back to a window. The picture that falls on his retina is virtually that of a flat surface; seeing it as such, he has to interpret the meaning of that picture ; and as he is more accustomed to see the solid form than the hollow mould, the latter is preferentially suggested to his mind. As another very curious instance of this kind of suggestion, I have here a mask, which I long ago got one of my sons to paint inside, just in the same way that the outside is usually painted. If this is held up so that there is no shadow, and a person looks into it steadily with one eye, the mental impression is that of projection. I was about to write a paper on Binocular Vision and the Stereoscope for the ‘Hdinburgh Review,’ and I asked the editor to come to my residence and see a few experiments. I placed him with his back to the window, and then, holding up this mask with the inside towards him, so that the light fell into it without causing shadow, I asked him to look at it with one eye, and to say what hesaw. He said at once that he saw the face of an ordinary mask. I then told him to open the other eye, and he was utterly astonished to find that he had been looking at the inside. Sir Charles Wheatstone told me that by long looking at a bust with his Pseudoscope, he had been able to reverse its relief; but that he could never do so with a living human face. And I have found that although, by crossing the pictures in the PROCEEDINGS OF THE SOCIETY. 493 Stereoscope, any conceivable reversion can be made, no such conversion of relief will take place when two portraits taken stereoscopically are thus crossed—the mind refusing to accept the suggestion. Having thus fully prepared my ground, I shall briefly deal with my proper subject. Prof. Abbe, as I understand him, says that the perception of relief in the case of the Binocular Microscope is some- thing different from that of ordinary stereoscopic vision ; and that it depends more upon the relative planes of portions of the object. I maintain, however, that it depends upon the combination (as in the Stereoscope) of two dissimilar perspective projections. We all know that the conception of solid form or projection which we get with the stereoscopic Binocular (in which the prism divides the cone of rays into its right-hand and left-hand halves), is very different from that which we get with the non-stereoscopic Binocular, in which half the rays of the entire cone are sent into each of the two bodies respectively. Lvery one also knows that in viewing a solid object he cannot get adequate focal depth with a very wide- angled objective. When our makers were bringing out 1/2 in. ob- jectives of very wide angles, up to 90°, I tried one of them on a slide of Polycystina, but could make nothing of it; for a portion of a spherical form (which was all that could be brought into focus) looked very much like the small end of an egg. When I reduced the angle to 60°, the same portion of a sphere looked like the large end of an egg; but when I further reduced the angle to 40°, I saw every form in its true projection. I got Mr. Powell to construct for me a 1/2 inch objective of 40°; and this has been the progenitor of a goodly off- spring of low-angled objectives, which give, in the Binocular, the real solid forms of opaque objects. I maintain that the pictures which we receive from the two lateral halves of such an objective, are as dissimilar as two portraits taken at an angle of 15°; and that it is by the stereoscopic combination of these, that the impression of solidity is suggested. It is interesting to go back to Mr. Wenham’s first paper on this subject,* written just thirty years ago. He was then working out the problem of the Binocular Microscope: rightly apprehending the principle of the Stereoscope, he attempted to reproduce its effects in the Microscope ; and you know how he ultimately succeeded, although his first results were unsatisfactory. Prof. Riddell also at first failed, and for the same reason,—that they both lost sight of the fact that as the Microscope itself reverses the pictures, it is neces- sary that they should be made to cross before reaching the eyes of the observer. Some among you will no doubt remember, that the first binocular Microscopes which were made, gave such a view of the objects, that though you sometimes saw them stereoscopically, the general effect was pseudoscopic. Now, Mr. Wenham in the course of his investigations did this;—he took a very suitable object for the purpose, the egg of a bug, and having put it under a 2/3 in. ob- jective, he covered up half the lens and made a drawing of the object * Trans. Micr. Soc., ii. (1854) p. 4. 494 PROCEEDINGS OF THE SOCIETY. as it then appeared; he then covered up the other half, and made another drawing. You can see for yourselves that these two figures are two dissimilar pictures; and I have found that they pair perfectly well in the Stereoscope, bringing out the object in relief. I have at home two photographs taken in the same way, showing by their combination precisely the same result. Another very curious piece of evidence, furnished by the dissimi- larity of the pictures given by the two lateral halves of a portrait- lens, will strengthen my case. In 1857 Mr. Claudet brought before the Royal Society this very interesting fact:— “I have noticed that when I hold my head in a certain position behind the focusing ground glass, I see the sitter, not as a flat picture, but as an image in relief. But this image is only to be seen when my head is in a certain place; if I move it to either side, or either forwards or backwards, I lose the effect.” He found the explanation of it to be, that in that particular position the picture taken by the left half of the lens came to his right eye, while the picture formed by the right half came to his left eye; whilst, if he moved so that he broke the lines of these two images, he lost the effect ; he further found that if he covered up either half of his lens, the solid image gave place to a flat picture, proving the combination of the two to be required to give the impression of solidity. He found that the effect of relief was most decided, when rays forming the picture were only allowed to pass through an aperture at each end of the horizontal diameter of the lens, all the rest being stopped out; while the appearance of solidity was lost when only the central portion of the lens was employed. Further, he found that the illusion of relief is not produced when the image was received on translucent paper instead of on ground glass; the reason of this difference being that, as all the molecules of the ground glass are in themselves transparent, though their surfaces are turned into lenses or prisms by grinding, some of the rays pass through it to the eyes; whilst, when the image is thrown upon paper, the rays are stopped by the opacity of its fibres, each molecule of which, becoming self-luminous, sends out its rays in all directions, so that one and the same picture of the object is seen by both eyes. Mr. Claudet obtained further proof of the correctness of his interpretation by placing a blue glass before one of the marginal openings of his portrait lens and a yellow glass before the other. The image seen when the eyes were in a position to receive and combine the two pictures was of a grey tint. But if one eye was closed, the image became blue; and if the other was closed, it became yellow,—the same effect being pro- duced by moving the head to one side or the other.* Although Mr. Claudet’s view of this matter was denounced by Sir D. Brewster as completely at variance with the laws of optics, yet he subsequently succeeded in establishing it beyond question by the construction of his Stereo-monoscope ; + in which the like effect was given by throwing on the same part of a ground glass, by two separate lenses, two * Proc. Royal Soc., viii. (1856-7) p. 569. + Ibid., ix. (1857-8) p. 194. PROCEEDINGS OF THE SOCIETY. 495 distinct pictures of the same object taken stereoscopically. These apparently coalesced into a single flat picture; but when the head was so placed that each eye received the rays issuing from the picture of the opposite side, the same effect of relief or projection was obtained, as if the two pictures had been combined by means of the ordinary Stereoscope. Now I cannot see how these facts are to be accounted for in any other way, than by the admission that the pictures formed of any object in relief, by the different parts of a lens of sufficiently wide angle of aperture, are sensibly different in their perspectives,—as a very simple construction shows that they ought to be. Thus, if we were to place a hexagonal prism under a lens of three times its own diameter (fig. 82), and were to take a picture of it first through the central circlet only, and then through each one of the peri- Fic. 82. pheral circlets in succession— all the rest of the lens being stopped out—we should have seven dissimilar pictures: that given by the central circlet showing only the hexagonal top of the solid, but in its true figure; whilst that formed by each of the peripheral circlets would give a foreshortened view of the hexagonal top, but would also bring in oblique views of three sides of the prism. Now, in the case described by Mr. Claudet, we should only receive the images from the two lateral circlets a b; and these “pair” so as to bring out the effect of relief, because they correspond with the two dissimilar perspectives which would be formed upon our two retine, if we were viewing the solid prism (enlarged to its apparent size) at the ordinary visual distance. But, it may be asked, if this is the real state of the case, how is it that we obtain anything like a distinct image of any solid projecting object viewed monocularly—that image being the com- posite resultant of a number of superposed pictures differing sen- sibly one from another. When the object is either flat or in low relief, the pictures will not sensibly differ, unless taken with a lens of much wider angle than the 40° which (as I have already stated ) I regard as the true limit for an objective to be used with the stereoscopic binocular. Now we have in Mr. Francis Galton’s remarkable “composite portraits,’ a proof that pictures even of different individual men, having the same general facial proportions, but expressions so different that each may be at once distinguished from the other, may be blended photographically into one image which would not be remarked-on as wanting in definition. And so the pictures formed of such an object as a Polycystine, Hucyrtidium 496 PROCEEDINGS OF THE SOCIETY. or Podocyrtis, by the several circlets (as in fig. 82) of a lens of 40° aperture, though actually different, will blend into a composite image —a sort of visual average. But when the two lateral halves of such a lens are made, by the stereoscopic binocular, to give to the right and left eyes respectively separate and sensibly dissimilar pictures, corresponding in their perspective projections to what the real object would give to the right and left eyes, if enlarged to the same size, and placed at 10 in. distance from them — then the visual con- ception of solidity is vividly called up. AsTI have already shown you, this conception may be excited also by other suggestions—a one-eyed person being able to see objects in relief, as a microscopist sees them in a monocular instrument. But there is nothing which so strongly and uniformly excites this visual conception of solid form, as the combination of the two dissimilar perspectives ; and this seems to me to be effected by the instrumentality of the Stereoscopic Binocular, exactly as (by Sir C. Wheatstone’s admirable demon- strations) we know it to be effected in ordinary binocular vision.* Mr. Crisp said that at that late hour he would compress into a brief compass his remarks in support of Prof. Abbe’s view. So far as Dr. Carpenter intended only to insist that stereoscopic vision in the Microscope resulted from two dissimilar images, there was no disagreement between himself and Prof. Abbe, and this being so, nearly all of Dr. Carpenter’s interesting discussion was not really in controversy so far as Prof. Abbe was concerned. The difference between Dr. Carpenter’s view and that of Prof. Abbe was as to the mode in which the two dissimilar images were formed. Dr. Carpenter suggested that they are formed in the Microscope just in the same way as in the case of the naked eye, i. e. perspectively ; whilst Prof. Abbe insisted that oblique vision in the Microscope is entirely different from that in ordinary vision, inasmuch as there is no perspective; so that we have no longer the dissimilarity which is the basis of the ordinary stereoscopic effect, but an essentially different mode of dissimilarity between the two pictures. If we look at asmall cube with the naked eye from an oblique direction it will be agreed that we shall see it as a perspective pro- jection upon a plane at right angles to the direction in which we are looking, with the well-known perspective shortening of all lines which are not parallel to that plane. In the Microscope, however, according to Prof. Abbe’s view, there is no such perspective shortening, but the cube is imaged in the manner described in his paper. That the latter is the correct view is proved by the fact that there is no difference in the outline of an object viewed under the Microscope by an axial or by an oblique pencil; there is simply a lateral displacement of the image—an entirely different phenomenon to that which occurs in non-microscopic vision. Again, in ordinary * [Addendwm.—I wish it to be distinctly understood, that in this discussion I refer exclusively to microscopic images formed dioptrically by objectives of low power and small angular aperture, and not to those formed (as Prof. Abbe has shown) by the combination of diffraction-spectra.—W. B. C.] { Ante, p. 20. See also i. (1881) pp. 422-3, PROCEEDINGS OF THE SOCIETY. 497 vision, a lined object will appear to have its lines closer and closer together according ag it is seen more and more obliquely. In the Microscope, however, we have the same number of lines to the inch whether the object is seen by an axial or an oblique pencil. This essential difference between naked-eye and microscopic vision by oblique pencils (which Prof. Abbe had been the first to point out) was most important to be kept in mind, as the opposite assumption had led to some of the greatest of the mare’s-nests of microscopy (“ All-round Vision,” &c.). The admission of this difference, however, did not invalidate any of the practical illustrations which Dr. Carpenter had given. The experi- ments of Mr. Claudet and Mr. Wenham, for instance, were performed with objectives of low aperture. Now the difference between the two modes of oblique vision varies as the cosine of the angle of obliquity, so that up to the limit of angle for objectives suitable for binocular work, say 40°, the difference does not exceed 1 per cent.—an amount quite inappreciable by the eye. Dr. Carpenter said he was not sorry to find that Prof. Abbe and himself were not so much in difference as he had thought to be the case. With large apertures, however, the whole conditions of vision were so entirely different that they could scarcely be com- pared; while, as regarded images of lines, they were so mixed up with diffraction effects that the question was necessarily in a very unsettled condition. If, however, Prof. Abbe was in agreement with him as to apertures under 40°, then clearly there was no question between them. The President, in proposing a vote of thanks to Dr. Carpenter, said that he was sure he was in accord with the unanimous feeling of all present, in expressing the gratification which Dr. Carpenter's presence that evening had afforded them. Mr, E. M. Nelson’s observations on the Bacilli of tubercle were referred to by Mr. Michael, who said that Mr. Nelson had found that when examined with dark-ground illumination they take the light in an unexpected and peculiar manner, appearing like grains of gold- dust on black velvet. The best effect was obtained by Swift's 140° condenser, with stop, illuminated by a lamp having a large-angled bull’s-eye accurately centered and focused, and the plane mirror. Excellent images are obtained by this method with a 2/3 in. and 1/2 in. eye-piece or a 4/10 and a 1 in. eye-piece. Mr. Nelson thinks three advantages accrue from this kind of illumination :—1st. The low power by which the organisms may be studied. 2nd. The great ease with which they may be detected in tissue; and 3rd. Saving to the eyes. Mr. Badcock described some observations he had recently made on some specimens of Surirella bifrons, which showed small processes similar to those found in the Arcellinw, and by means of which the diatoms seemed to be moved to and fro (see p. 352). Ser. 2.—Vou. IV. 2 L 498 PROCEEDINGS OF THE SOCIETY. Mr. Guimaraens described a slide showing a true Xanthidium in Halifax coal strata, discovered by Mr. James Spencer, of Halifax, who also prepared the slide. Mr. Bolton’s note was read on the finding in Epping Forest of the Rhizopod Clathrulina elegans, which forms a transition from the fresh-water Heliozoa to the marine Polycystina. This was, Mr. Bolton believed, the first discovery of it in England. Mr. Crisp asked that any Fellows finding Megalotrocha albo- flavicans, or Lacinularia socialis, would send living specimens to Dr. C. T. Hudson, who was much in want of them for his forthcoming work on the Rotatoria. The President announced that the following resolution had that evening been passed by the Council, and gave notice that a special meeting of the Society would be held on the 14th May next, for the purpose of taking it into consideration, and passing such resolutions as might be considered desirable, whether by alteration of the by-laws or otherwise :— “That it is expedient that ladies should be admitted as members of the Society, either as Fellows or Associates, or under such other title as the Society shall determine, provided that they shall not attend the ordinary meetings.” The President also announced that in consequence of the change of librarian, the second Conversazione would be omitted for this session. The following Instruments, Objects, &c., were exhibited :— Mr. Badcock :—Slide in illustration of his paper. Mr. Bolton :—Clathrulina elegans. Dr. Carpenter :—Photographs in illustration of his paper. Mr. Crisp :—Paraboloid for rotating illumination in azimuth. Mr. Guimaraens :—Xanthidium in Halifax coal strata. New Fellows.— The following were elected Ordinary Fellows :— Messrs. Charles Botterill, Aristides Fournet, Rev. T. M. Gorman, Henry Gradbe, M.D., G. Massee, Benjamin Owen Meek, Gerald Sturt, and John Michael Williams. PROCEEDINGS OF THE SOCIETY. 499 SpectAL AND Orpinary Mertines oF 14th May, 1884, av Kina’s CotuecE, Stranp, W.C., raz Presment (Rey. W. H. Darunaer, F.R.S.) in tHE CHarr. The President, in opening the special meeting (called for the purpose of considering the proposed admission of ladies as Fellows of the Society), requested Mr. A. D. Michael to move a resolution. Mr. Michael said he found himself unexpectedly charged with the resolution under circumstances which he would explain. He thought he should not be making any unnecessary disclosure by saying that the Council were led to the consideration of the matter by an application which was received from a Fellow of the Society (Sir Henry W. Peek, Bart., M.P.), inquiring if it was in order for him to nominate a lady as a Fellow of the Society. Being thus appealed to, the Council considered the matter, and on its being found that under their present by-laws it was not possible to do what was asked, some of the Council were of opinion that it would be desirable to admit ladies, pure and simple. He, for one, however, was not able to see his way clear to agree with so large a proposition, and his share in the matter was connected with the proviso at the end of the resolution which was approved by the majority of the Council. As it thus originated with him, he became charged with the duty of submitting it to the meeting. The feeling of the Council, as expressed by the resolution, was that there could be no objection to ladies being admitted as Fellows, provided that they did not attend the ordinary meetings. For his own part, he could not but see grave objections to the admission of ladies at the ordinary meetings, because in the course of their proceedings subjects were often intro- duced which English gentlemen could not freely discuss in the presence of ladies. At least, this had been found to he the effect at other societies where ladies had been admitted without limitation. For this reason he was opposed to the proposal as originally made; but if there was a feeling that ladies should be admitted to the other privileges of the Society—the library, the instruments, Journal, &c., he did not see any objection to it. He thought that probably the majority of the very few ladies who might be called practical workers with the Microscope would desire to share in those privileges only, and that those who could give the Society the most assistance would not, under any circumstances, attend the meetings. He also wished it to be understood that in moving the resolution there was no desire on the part of the Council to force the matter upon the Fellows. All that was intended was to submit the question to them for their con- sideration and to invite discussion upon it. With this view he moved —‘ That ladies shall be eligible as Fellows of the Society, and shall be subject to all the obligations and entitled to all the privileges of Fellows, except that they shall not be entitled to attend the ordinary meetings of the Society.” Dr. Anthony seconded the motion. Mr. Crisp called attention to the fact that a special notice of this meeting had been posted to all Fellows in the United Kingdom. 2% 2 500 PROCEEDINGS OF THE SOCIETY. Dr. Coffin moved as an amendment that the last fifteen words of the resolution (from and including the word “ except”) be omitted, so that ladies should be admitted to all the privileges of Fellows, including attendance at the ordinary meetings. No one rising to second the amendment, the President put the original resolution to the meeting, and declared it to be carried. The special meeting then terminated. The List of Donations (exclusive of exchanges and _ reprints) received since the last meeting, was submitted, and the thanks of the Society given to the donors. From Catalogue des Collections du Musée de l’Industrie. 241 pp. 8vo, Bruxelles, 1846 .. .. .. «2 «. « « « Le Bibliothécaire. Musée R. de l’Industrie—Bibliothéque Technologique—Cata- logue. 275 pp. 8vo, Bruxelles, 1878 .. .. .. .. 45 Slides illustrating vol. i. of the ‘Monograph of British Oribatidse Moke (stegbcoMrMkowt Musial guksc wisaup Weebimimels RAL el seMachaels Slide of Halecium halecinum .. 1. 1. 22 ewe .. Mr. H. C. Chadwick. Slide of Objects found in Flue-dust and Coal-ash .. .. .. Miss Dancer. Slides of Sand obtained by washing clay from the boulder drift of; Minnesota dike. tesa taca yes Glee oun) cee, tonne ep a mA ehomas: Mish=troug hs sec ojcisie party Vian geese tas Pu nak waltemeos panetcn alls ARV ay Stokes Ditto. The following letter from Mr. Michael referring to his donation was read :— “T send the type series of British Oribatide which I proposed giving to the Society. It corresponds exactly with vol. i. of my work on the British Oribatide, just published by the Ray Society. The series includes all the species mentioned in the book, except two, of which I have not any duplicates. It also includes many of the immature stages. I have marked the slides with a running number so that if they get out of order they can at once be restored to the arrangement of the book. I have also put a separate list of the slides with them. Blanks are left for the two species of which I do not possess duplicates. Should I obtain any at any time I will fill up these blanks; I shall also hope to deposit a similar series illustrating the second volume, whenever that shall be published. I have announced in the preface of the book that the types have been deposited with the Royal Microscopical Society. Finally, I venture to hope that others may follow my example, and that it may assist in ultimately placing the Society in possession of such a collection of typical and interesting slides as it ought to have.” Dr. C. H. Golding-Bird exhibited and described his new freezing microtome, which was intended to be put into the hands of students and intermittent workers. It was graduated to cut sections of less than the 1/1C00 in. in thickness, whilst in one form it was adapted for the use of ice and salt, and in another for use with ether spray. Mr. Groves, in reply to the President, said that he had had the PROCEEDINGS OF THE SOCIETY. 5OL pleasure of seeing and examining the microtome, and it seemed to him to be a most perfect and useful little instrument. The President considered one of its advantages to be that it maintained the temperature at the same point for a much longer period than most others. Dr. P. Herbert Carpenter gave an account of his views respecting the nervous system of the Crinoidea, which he illustrated by diagrams drawn upon the board, and by numerous preparations exhibited under Microscopes. He directed attention more particularly to the branches from the axial cords of the skeleton, which extended upwards into the ventral perisome at the sides of the ambulacra both of the arms and of the disk. The material was chiefly derived from the collection of the ‘Challenger’ expedition, and the results when complete will be embodied in the volume in course of preparation. Dr. Carpenter, C.B., said he was very glad that his son had brought this subject forward, because it formed an extremely good illustration of the value of microscopical investigation where important questions had to be determined. In this instance a great deal hung upon the point whether these cords were nerves or not; for if they were, then it was clear that the whole of their present system of classification of Echinodermata must undergo revision, because all morphologists had been trying to show the analogy of this group to the star-fishes, of which they were considered to be only a family. He had, however, always held, from a careful study of them during the last thirty years, that the general structure of the crinoids was formed upon a plan very different from that of the star-fishes. Of the various argu- ments which his son had brought forward to prove the truth of that idea, the anatomical argument was the most important, as being a confirmation of what he had himself previously advanced ; for it must be remembered that at the time to which he had referred, many things could not be demonstrated because they had not then known how to cut thin sections. Very early in his investigations he had found that a cord which had been discovered by Miiller, and consi- dered by him to be a nerve, was a genital rachis, which would develope afterwards according to the sex of the specimen. But by the adoption of thin section-cutting a flattened band was discovered beneath the ambulacral groove, which all the German observers, and Professor Huxley also, at once concluded to be the nerve, because a nerve ought to be there. In the star-fishes it certainly was so; but it was certainly not the only nerve in crinoids. He was early led to regard as a nerve a cord running continuously through the calcareous segments of the arm, and originating in a central organ in the base of the calyx. This organ, which is an expansion of the summit of the original crinoid stem, is divided into five chambers, from the outer walls of which proceed five radial branches ; and these branches inosculate with each other laterally so as to form a circular commissure from which branches are given off to the arms, thus establishing a nervous con- nection amongst them all, of which no one could doubt the existence who has ever seen these feather-stars in the act of swimming, or simul- 502 PROCEEDINGS OF THE SOCIETY. taneously coiling up their arms on irritation of the oral pinnules which arch over the mouth. He had experimented upon the matter in various ways. Having turned out the visceral sac, he passed a needle down and irritated this central organ, and immediately all the arms coiled up together. Again, he turned out the visceral mass entirely, thus getting rid of the centre of the ventral nerve-system, and put the animal—which then consisted of a mere skeleton—into the water ; it swam just as well as before, with the same beautifully co-ordinated movements of its ten arms. He then tried the experiment of dividing this ventral nerve, but found that it did not paralyse any of the parts beyond. But when he removed the centro-dorsal cup containing the central organ of what he regarded as the dorsal nervous system, the whole of the arms were tetanized, from the contraction of the ligaments without any muscular antagonism. He then endeavoured to cut through this nerve without separating the arm ; but was unable to do this successfully, as the animal threw off the armat once. He there- fore contrived to burn it away with nitric acid, and then found that the arm was paralysed. These experiments, and the anatomical descriptions which his son had given, so entirely agreed that he thought there was no getting over the proof that the muscular apparatus of the arms of crinoids is put in action, not by a ventral nerve-system homologous with that of other Echinoderms, but by a dorsal nerve-system peculiar to themselves. He thought they were perfectly conclusive ; and referring to the well-known story of George Stephenson and the cow, thought that if the homologists still persisted in going against the facts, somuch the worse for the homologists. What, therefore they had to do was to ascertain exactly what was the true morphology of the crinoid; and it seemed to him that its most beautiful skeleton was more like that of the Vertebrata, because it was modelled upon a nervous system. The joints of the crinoidal stem, and all the segments of the rays which issue from its summit are penetrated by a canal for the nerve-cord ; but this canal is not found in the dermal or accessory plates which constitute a large part of the skeleton of many fossil crinoids. The existence of this canal became, therefore, of great importance; if it was a canal for the passage of a nerve, then it became a fundamental feature in the organization of a crinoid. The crinoids were exceptional also for the wonderful activity of their movements; no star-fish certainly had anything like the activity or co-ordinated movements of a'criroid. He thought, then, that they ought to say that the skeleton which incloses the nervous system is the fundamental basis of the crinoid; and that there was but a very imperfect analogy between it and that of the star- fishes. The question afforded, to his mind, a very important lesson as to not allowing theory to go against fact ; and also that microscopical examination was of the greatest value in the determination of questions of this kind. Dr. Matthews inquired what reagents were employed by Dr. P. H. Carpenter in the preparation of his specimens. Dr. P. H. Carpenter said he had used hematoxylin sometimes, also osmic acid, or picro-carmine or borax-carmine. PROCEEDINGS OF THE SOCIETY. 503 Herr H. Boecker’s collection of slides of Bacteria, Bacilli, & , exhibited in the room, were referred to by Mr. Crisp as one of the best yet seen in this country. Mr. Crisp exhibited a curious Microscope, with a sliding nose- piece for three objectives, marked “ Joseph Brum, Opticus in Instituto Bononie, F.A., 1772,” but identical (except the nose-piece) with plate II. in the 4th edition of G. Adams, sen.’s treatise on the Microscope (1771). The nose-piece was an anticipation of the plan adopted in more modern times in the Harley Microscope and others. He also exhibited the two Microscopes by Reichert and the apparatus mentioned in the list of exhibits. Mr. Griffith’s multiple eye-piece was exhibited by Mr. Crisp, and discussed by Dr. Matthews, Mr. Powell, and others. Mr. Crisp mentioned that notice had been received that the American Society of Microscopists would hold their annual meeting at Rochester, N.Y., on the 19th of August next, and as their President, one of the Vice-Presidents (Mr. Glaisher), and a member of the Council (Mr. A. W. Bennett), were going to Canada, the Council had resolved, subject to the confirmation of the Fellows, to ask them to attend the meeting as a deputation from this Society. The proposal having been put to the meeting, was approved unanimously. : The following Letter and Report were read and ordered to be entered on the minutes :-— : “New York, March 31st, 1884. Dear Srz,—At a regular meeting of the New York Microscopical Society, held on the evening of the 21st instant, at No. 64, Madison- avenue, the report of the Committee appointed to present in a formal manner the sentiments of the Society in view of the death of Mr. Robert B. Tolles was read and accepted. On motion it was ordered that a copy of said report be sent to the ‘American Monthly Microscopical Journal’ and the ‘ Royal Microscopical Journal.’ I have the honour herewith to enclose a copy as stated. Iam, &c., Epwarp G. Day, Mr, Frank Crisp, Sec. Royal Microscopical Society. Cor. Sec.” “ Your Committee, appointed at the meeting held December 21st, to present in a formal manner the sentiments of the Society, in view of the death of Mr. Robert B. Tolles, find in the remark made by Mr. William Wales at that meeting a fitting and satisfactory expression of said sentiments. Mr. Wales said in substance :— ‘The death of Mr Tolles has been to me a source of deep regret. yor modesty, for uprightness, for earnestness of purpose, he was one of the most estimable of men. A larger capacity than his, a firmer 504 PROCEEDINGS OF THE SOCIETY. and finer skill, a more artistic feeling, a sterner conscientiousness, has seldom, if ever, been devoted to the work of making the Microscope a thoroughly efficient and trustworthy aid in scientific research. The fortunate owner of one of his fine lenses possesses one of the most exquisite pieces of mechanism ever produced by the mind and hand of man. Mr. Tolles loved his beautiful art. He loved it better than riches ; for he died a poor man. He loved it better than life; for its pursuit, necessitating the constant inhalation of glass dust, shortened his days. The labours of such a man entitle him to the lasting esteem and gratitude of all lovers of the Microscope, as well as of that field of investigation to which this instrument is the indispensable portal.’ ” Mr. B. W. Thomas’s slides of sand obtained by washing clay from the boulder-drift of Meeker county, Minn., U.S.A., were explained by Mr. Crisp. In similar specimens, Professor Leidy had recognized some well-preserved and characteristic Foraminifera, of which two forms appeared identical with Teatularia globulosa and Rotalia globulosa, now living in the Atlantic Ocean. The fossils Mr. Thomas supposes to be derived from a soft yellow rock, cretaceous shale and lignite forming part of the drift. He also reports the finding of fragments of marine diatoms in the clay. The following Instruments, Objects, &c., were exhibited :— Dr. C. H. Golding-Bird :—Microtome. Mr. H. Boecker :—Slides of Bacteria, Bacilli, &e. : Mr. Chadwick :—Halecium halecinum, mounted as described ante, pi dlials 2 Mr. Cheshire :—Curious form of Spirillum. Mr. Crisp :-— (1) Old Microscope. 2) Reichert’s Microscope, with modified Abbe Condenser. 3) Reichert’s Polarization Microscope. (4) Griffith’s Multiple Eye-piece. (5) Glass Frog-plate. (6) Getschmann’s Slides of arranged Diatoms, &e. (7) Bradley’s ‘ Mailing Boxes.” Miss Dancer :—Objects found in flue-dust and coal-ash. Mr. Guimaraens:—The slide of Xanthidium exhibited at the last meeting. Mr. A. W. Stokes :—Fish-trough. Mr. B. W. Thomas :—The slides mentioned supra. Dr. G. C. Wallich:—A Rotalian from closed flint nodular cavity metamorphosed into chalcedony. New Fellows :—The following were elected Ordinary Fellows :— Messrs. Henry W. Fuller, H. A. Johnson, M.D., James C. Stodder,. H. Thomas, M.D., and G. F. Turton. STAINING FLUIDS, | Sea ee AR. & J BECK, SAA. Manufacturing Opticians, _ ‘N 68, CORNHILL, LONDON, EC, \ |. FACTORY: \ LISTER WORKS, HOLLOWAY. | New Double-Diaphragm & Iris Diaphragm Achromatic Oondensers of Wide Angle. _ HIGH-POWER OBJECT GLASSES — FOR THE BINOCULAR. PATHOLOGICAL AND Oo ’ PHYSIOLOGICAL PREPARATIONS. | eS MICROTOMES, |) ALL : ) OTHER REQUISITES — FOR MOUNTING. SSE -'NEW “PATHOLOGICAL”? MICROSCOPE. - Full Catalogues sent Free on application to. R. & J. BECK, 68, CORNHIEL, LONDON, E.C. (BR) _ -W. WATSON & SON'S NEW MICROSCOPE STAND bee ae The most perfect Instrument for the employment of light at great angle of obliquity ever introduced. W. & Ss PATENT MECHANICAL STAGE Is graduated to degrees—Rotates concentric, and will revolye completely round, with any instrument—has mechanical movements in vertical, horizontal, and: oblique ‘directions, and is the thinnest and most perfect. mechanical stage ever introduced, See description i in the Royal Microscopical Journal, April and June, 1881, Tlustratea Catalogue of above, and all descriptions of Microscopes and Apparatus, post free 2d. -W. ‘WATSON & SONS, 313, High Holborn, London, W. 0. TAMES EIOW & CO., SUCCESSORS TO GEO. KNIGHT. & SONS, poe 73, FARRINGDON ST. (late of 2, Foster Lane, and 5, St. Bride St). _ HOW’S MICROSCOPE LAMP, THE MINIATURE MICROSCOPE LAMP. HOW'S STUDENTS’ MICROSCOPE, £5 5s.. THE POPULAR BINOCULAR sae aha £12 128. Rock SECTIONS AND OTHER MicKoscoric OBJECTS. ~ New and Second- hand Microscopes, Obj ectives, and Accessories. A Large Assortment by Ross, Bec; Coriis, Swirt, and other first-class Makers, on Sale, j ata GREAT REDUCTION IN PRICE. ; MICROSCOPICAL OBJ. ECTS i in great variety. Spécialité. Puystorocrcoan and PaTHOLOGIOAL Tissurs. A-chorce vartety of prepared Physiological Sections ready for Mounting. PHOTOGRAPHIC LENSES, CAMERAS, and APPARATUS, by Ross, DaLLueyer,-and all other Geecmod Makers. Largest, Cheapest, and Best Stock 'in London. New Cararoeuzs Post Free. Spee & HUNTER, 90, CRANBOURN STREET, LONDON. LIVING SPECIMENS FOR THE MICROSCOPE. GOLD MEDAL awarded at the FISHERIES EXHIBITION to ‘THOMAS BOLTON, 57, Newhall Street, Birmingham. ‘SPECIMEN TUBE, ONE SHILLING. A Series of TWENTY-Stx Tuses in‘ course of Six Months (or ag required) for a ad -. in advance, of £1 Is. Portfolio of Drawings, Ten Farts; One Shilling each, EBDWARD WARD’S BROWN CEMENT. This Cement was first introduced to Microscopists in a paper read before the Manchester Science Asso- ciation, on Jan, 26th, 1880. Its” Success has. been 50, marked that many imitations have been sold tinder the same or sintilar names. —~ ~ Purchasers should see:that: they’ are furnished with WARD'S Brown Cement, which eel be obsuned from many. Dealers, price 1s. ; or direct: fromthe Preparer, post-free, for 1s, 3d. NEW SLIDE OF POLYZOA (BUGULA PLUMOSA), — With tentacles extended, stained and mounted in Balsam. Post-free for 1s. 8d. “EDWARD: WARD, 249, OXFORD STREET, MANCHESTER (nearly opposite Owens College). fs NOTICE OF REMOVAL. | THOMAS D. RUSSELL, late of Essex Srreen, Srranp, has femovel his extensive - Collections of British ‘and Foreign Shells; Crustacea, Echinoderms, - Corals, Fossils, ' Minerals, Rocks, Microscopic: Objects, &e., to more convenient and spac PE eses, NEAR THE NEw: GENERAL Post OFFIce. THOMAS D. RUSSELL, 78, 8, Newgate Street, London. B.C. Cla 5. International Exhibition Prize Medals and Awards, 1851, 1856, 1862, 1873, 1878; and The Imperial Austrian Francis Joseph Order; for Excellence and Cheapness, M. PILLISCHER’S NEW MICROSCOPE, “THE INTERNATIONAL,” Is furnished with B and © Hye-pieces; a 5-8 and 1-7 Object-glasses of high defining cae penetrating quality, combining (by a draw-tube) a series of eight different powers, from 50 to 420 diameters 5 bull’s-eye con- sue denser; revolving diaphragm; pair of tweezers; plate-glass slips and thin covering glass, and a well-made mahogany box, 10: by:6 by 4, with lock and key . .. Price £47 10s. With the addition of A Eye-piece, 14 or 2 in. Object-glass, Polarising Apparatus and Selenite, and a Camera Lucida... Price £10 103. And all the Apparatus and ‘Accesories, as described above, “With the addition of a D-Hye-piece and a 1-9 Object-glass, giving a Series of she aloe magnifying powers, from-15 to 1000 diameters ..~. Price £14 Os. A Glass Stage, to prevent the instrument from being alfected by the w use eof corrosive chemicals, to any of the above instruments... ee ee 12s. 6d. Illustrative Descriptive Catalogue on application to 88, NEW BOND STREET, earns WV FRED. ENOCK,. PRESARER OF INSECTS, AND PARTS OF INSECTS, FOR THE ‘vicroscore, ae WiTH AND -WitHouT PRESSURE, THE LATTER RETAINING NATURAL FORM AND COLOURS. Sallnecven: WOKING STATON SPECIAL NWOTICE POWELL AND LEALAND’S| NEW OIL IMMERSION CONDENSER can be adapted to any Microscope, and. resolyes all the most difficult test objects—price Two Guineas. MICROSCOPES from £11 11s. to £200. The £11 11s. Instrument consists of 1-inch and }-inch Object-glasses, with Apertures of 30 and 95 deg. respectively, coarse and fine Adjustment, Glass Stage and Bull’s-eye Condenser, fitted in mahogany case, and is most suitable for Students, Brewers, &c. WATER AND OIL IMMERSION LENSES. — : Manufactory : 170, EUSTON ROAD, LONDON, N.W. oo ORAS. - COLLINS: | HISTOLOGICAL MICROSCOPE, Q With 1-inch and 3-inch Objectives of splendid Definition, Eye-piece, and Case, £5 10s. Full particulars free per post. Harloy Binocular Microscopes, Dissecting Microscopes, Lamps, Objectives, Thin Glass Slips, Mediums, and every requisite for the Study. : THIRTY-SIX PAGE ILLUSTRATED CATALOGUE (ON APPLICATION. CHARLES COLLINS, 157, Great Portiand Street, London, W. _W. P, Coxtans’ Science Book Depét, adjoining the above. Catalogue on application, CY HEN RY cROUCH’S MICROSCOPES. INTENDING PURCHASERS of MICROSCOPES are invited to apply for a CATALOGUE, fully Illustrated, and giving full particulars of INSTRUMENTS of the LATEST CONSTRUCTION, devised for every class of investigation. BARBICAN OPTICAL WORKS, 66, BARBICAN, Ef “MICROSCOPIC OBJECTS. Classified. Cataloque, NEW EDITION FOR 1880. Post Free and Gratis, ‘Specimens of the highest attainable perfection in every branch of Microscopy. New and Rare Diatomacex. Test and Binocular Objects. Moller’s Typen Plattes. Microscopes, Achromatic ‘Objectives, and all Materials and Instruments for Mounting. ~ EDMUND ee A8B, Tollington Road, Holloway, London, N. NATURAL HISTORY and GENERAL SCIENCE. THE LARGEST COLLECTION OF SECOND-HAND WORKS RELATING 10 ye ABOVE. é Catalogues to be had at . : JOHN WHELDON’S, 58, GREAT QUEEN STREET, ‘LONDON, wee A Pamphlet just published by JAMES Swirr, entitled THE MICROSCOPE AND ACCESSORY Pas ' NOTES ON THE CONSTRUCTION, SELECTION, “AND USE. By post, 24 Stamps. “Also, EUs. £ LLUSTRAT ED. CATALOGUE Of New Microscorss, APPARATUS, and Oxsxorivss, for 6: Stamps. NEW OIL-IMMERSION 1-12 INCH OBJECTIVE, PRICE £1210 SWIET AND SON, University Optical Works: 81, TOTTENHAM COURT. ROAD, LONDON, W. ‘STUDIES IN MICROSCOPICAL SCIENCE. Epitep sy ARTHUR C. COLE, F.R.M.S. SECTION L—-ANIMAL HISTOLOGY. —This portion of ne Work awill be tssued tn. “Montuy ‘Numbers, commencing with No. 1; on the Ith July, 1883, at an Annual Subscription of £1 1s., payable in advance. Tt will consist of \a systematic treatise: on comparative: histology; illustrative types will. be chosen and ~ described fully, and will be accompanied by mictoscopical preparations and lithographed plates. : Section I1,.—BOTANICAL HISTOLOG Y.— This portion of the Work will be issued in Monthly Numbers, commencing with No. 2, on the 21st July; 1883, at an Annual Subscription\of £1 1s., payable im advance. The work will be conducted on the lines indicated for Section T. d Each Section will be paged separately, so as to give Subscribers the option of purchasing either. % Section IIT.—POPULAR “MICROSCOPY.—Publication to commence on the 14th July, 1883, ‘and to: continue monthly thereafter. Aseries of Popular Objects will be issued. Hach» number) will: contain’ a ~~ preparation, a lithograph, and ‘descriptive letterpress, with methods’ of preparation, &e., ‘of the object asuey SUBSCRIPTION, £1 1s., payable in advance. - A Detailed Prospectus, with List. of Prepakations, &c., may ‘be obtained on application to the Editor— Ra a Domingo Housn, OxrorpD GarbEens, NortinG Hixt, Lonbon, Wi. : Nas : ¢ 15 x 33 Council Medal and Highest award, Great Exhibition, London, 1851. ; Gold Medal, Paris Exposition, 1867. ' Medal and Highest Award, Exhibition, London, 1862. Medal and Diploma, ‘Centennial Exhibition, Philadelphia, 1876. Medal and Diploma, Antwerp, 1878. - Gold Medal and Diploma, Paris Exposition, 1878. Medal, Highest Award,-Sydney, 1879. ROSS & CO., ie MANUFACTURING OPTICIANS, | 112, NEW BOND STREET (FACTORY, BROOK STREET), LONDON, W. ‘MICROSCOPES, OBJECT-GLASSES, APPARATUS, “MICROSCOPIC PREPARATIONS. | be NW EW. : as ‘DESCRIPTIVE CATALOGUE — ROSS & CO. 112, NEW BOND STREET, Ww. (One door from Brook Street), REMOVED FROM 164, NEW BOND STREET. ESTABLISHED 1880. THE ROYAL MICROSCOPICAL SOCIETY. - Founded in 1839, Incorporated by Royal Oharter in 1866,) - The Society was established for the communication and discussion of observations and discoveries (1) tending to improvements in the con- struction and mode of application of the Microscope, or (2) relating to Biological or other subjects of Microscopical Research. ~ It consists of Ordinary, Honorary, and Ex-officio Fellows. Ordinary Fellows are elected on a Certificate of Recommendation signed by three Fellows, stating the names, residence, description, &c., of the Candidate, of whom one of the proposers must haye personal know- ledge. The Certificate is read at a Monthly Meeting, and the Candidate -balloted for at the succeeding Meeting. — zs ; The Annual Subscription is 27. 23., payable in advance on election, and subsequently on Ist January annually, with an Entrance Fee of 21, 2s. Future payments of the former may be compounded for at any time for 311. 10s. Fellows elected at a meeting subsequent to that in February are only called upon for a proportionate part of the first year’s subscription, — and Fellows absent from the United Kingdom for a year, or permanently residing abroad, are exempt from one-half the subscription during absence. — Honorary Fellows (limited to 50), consisting of persons eminent — in Microscopical or Biological Science, are elected on the recommendation ‘ of three Fellows and the approval of the Council. Ex-officio Fellows (limited to 100) consist of the Presidents for the time being of such Societies at home and abroad as the Council may recommend and a Monthly Meeting approve. - They are entitled to receive the Society’s Publications, and to exercise all other privileges of Fellows, except voting, but are not required to pay any Entrance Fee or Annual Subscription. : The Council, in whom the management of the affairs of the Society is vested, is elected annually, and is composed of the President, four Vice- | Presidents, Treasurer, two Secretaries, and twelve other Fellows, The Meetings are held on the second Wednesday in each month, | from October to June, in the Society’s Library at King’s Oollege, Strand, W.C, (commencing at 8.p.m.). Visitors are admitted by the introduction of Fellows. Ge 2, roe In each Session two additional evenings are devoted to the exhibition of Instruments, Apparatus, and Objects of novelty or interest relating to the Microscope or the subjects of Microscopical Research. The Journal, containing the Transactions and Proceedings of the - Society, with a Summary of Current Researches relating to Zoology and Botany (principally Invertebrata and Cryptogamia), Microscopy, &c., is published bi-monthly, and is forwarded gratis to all Ordinary and Ex-officio Fellows residing in countries within the Postal Union. The Library, with the Instruments, Apparatus, and Cabinet of — Objects, is open for the use of Fellows daily (except Saturdays), from 10 A.M. to 5 P.M., and on Wednesdays from 7 to 10 p.m. It is closed during August. Page ist Forms of proposal for Fellowship, and any further information, may be obtained by application to the Secretaries, or Assistant-Seorctary, at the Library of the Society, King’s College, Strand, W.C. 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